diff --git a/include/mbedtls/ecjpake.h b/include/mbedtls/ecjpake.h
index 3d8d02a..00e752b 100644
--- a/include/mbedtls/ecjpake.h
+++ b/include/mbedtls/ecjpake.h
@@ -75,7 +75,7 @@
  */
 typedef struct mbedtls_ecjpake_context
 {
-    const mbedtls_md_info_t *md_info;   /**< Hash to use                    */
+    mbedtls_md_handle_t md_info;        /**< Hash to use                    */
     mbedtls_ecp_group grp;              /**< Elliptic curve                 */
     mbedtls_ecjpake_role role;          /**< Are we client or server?       */
     int point_format;                   /**< Format for point export        */
diff --git a/include/mbedtls/hkdf.h b/include/mbedtls/hkdf.h
index 40ee64e..ebf5e12 100644
--- a/include/mbedtls/hkdf.h
+++ b/include/mbedtls/hkdf.h
@@ -70,7 +70,7 @@
  *  \return An MBEDTLS_ERR_MD_* error for errors returned from the underlying
  *          MD layer.
  */
-int mbedtls_hkdf( const mbedtls_md_info_t *md, const unsigned char *salt,
+int mbedtls_hkdf( mbedtls_md_handle_t md, const unsigned char *salt,
                   size_t salt_len, const unsigned char *ikm, size_t ikm_len,
                   const unsigned char *info, size_t info_len,
                   unsigned char *okm, size_t okm_len );
@@ -99,7 +99,7 @@
  *  \return An MBEDTLS_ERR_MD_* error for errors returned from the underlying
  *          MD layer.
  */
-int mbedtls_hkdf_extract( const mbedtls_md_info_t *md,
+int mbedtls_hkdf_extract( mbedtls_md_handle_t md,
                           const unsigned char *salt, size_t salt_len,
                           const unsigned char *ikm, size_t ikm_len,
                           unsigned char *prk );
@@ -130,7 +130,7 @@
  *  \return An MBEDTLS_ERR_MD_* error for errors returned from the underlying
  *          MD layer.
  */
-int mbedtls_hkdf_expand( const mbedtls_md_info_t *md, const unsigned char *prk,
+int mbedtls_hkdf_expand( mbedtls_md_handle_t md, const unsigned char *prk,
                          size_t prk_len, const unsigned char *info,
                          size_t info_len, unsigned char *okm, size_t okm_len );
 
diff --git a/include/mbedtls/hmac_drbg.h b/include/mbedtls/hmac_drbg.h
index f1289cb..ed03854 100644
--- a/include/mbedtls/hmac_drbg.h
+++ b/include/mbedtls/hmac_drbg.h
@@ -138,7 +138,7 @@
  *                      MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED.
  */
 int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx,
-                    const mbedtls_md_info_t * md_info,
+                    mbedtls_md_handle_t md_info,
                     int (*f_entropy)(void *, unsigned char *, size_t),
                     void *p_entropy,
                     const unsigned char *custom,
@@ -158,7 +158,7 @@
  *                      MBEDTLS_ERR_MD_ALLOC_FAILED.
  */
 int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx,
-                        const mbedtls_md_info_t * md_info,
+                        mbedtls_md_handle_t  md_info,
                         const unsigned char *data, size_t data_len );
 
 /**
diff --git a/include/mbedtls/md.h b/include/mbedtls/md.h
index 69ab21f..40624e4 100644
--- a/include/mbedtls/md.h
+++ b/include/mbedtls/md.h
@@ -85,13 +85,17 @@
  */
 typedef struct mbedtls_md_info_t mbedtls_md_info_t;
 
+
+typedef struct mbedtls_md_info_t const * mbedtls_md_handle_t;
+#define MBEDTLS_MD_INVALID_HANDLE ( (mbedtls_md_handle_t) NULL )
+
 /**
  * The generic message-digest context.
  */
 typedef struct mbedtls_md_context_t
 {
     /** Information about the associated message digest. */
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
 
     /** The digest-specific context. */
     void *md_ctx;
@@ -120,7 +124,7 @@
  * \return          The message-digest information associated with \p md_name.
  * \return          NULL if the associated message-digest information is not found.
  */
-const mbedtls_md_info_t *mbedtls_md_info_from_string( const char *md_name );
+mbedtls_md_handle_t mbedtls_md_info_from_string( const char *md_name );
 
 /**
  * \brief           This function returns the message-digest information
@@ -131,7 +135,7 @@
  * \return          The message-digest information associated with \p md_type.
  * \return          NULL if the associated message-digest information is not found.
  */
-const mbedtls_md_info_t *mbedtls_md_info_from_type( mbedtls_md_type_t md_type );
+mbedtls_md_handle_t mbedtls_md_info_from_type( mbedtls_md_type_t md_type );
 
 /**
  * \brief           This function initializes a message-digest context without
@@ -182,7 +186,7 @@
  *                  failure.
  * \return          #MBEDTLS_ERR_MD_ALLOC_FAILED on memory-allocation failure.
  */
-int mbedtls_md_init_ctx( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info ) MBEDTLS_DEPRECATED;
+int mbedtls_md_init_ctx( mbedtls_md_context_t *ctx, mbedtls_md_handle_t md_info ) MBEDTLS_DEPRECATED;
 #undef MBEDTLS_DEPRECATED
 #endif /* MBEDTLS_DEPRECATED_REMOVED */
 
@@ -205,7 +209,7 @@
  *                  failure.
  * \return          #MBEDTLS_ERR_MD_ALLOC_FAILED on memory-allocation failure.
  */
-int mbedtls_md_setup( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info, int hmac );
+int mbedtls_md_setup( mbedtls_md_context_t *ctx, mbedtls_md_handle_t md_info, int hmac );
 
 /**
  * \brief           This function clones the state of an message-digest
@@ -238,7 +242,7 @@
  *
  * \return          The size of the message-digest output in Bytes.
  */
-unsigned char mbedtls_md_get_size( const mbedtls_md_info_t *md_info );
+unsigned char mbedtls_md_get_size( mbedtls_md_handle_t md_info );
 
 /**
  * \brief           This function extracts the message-digest type from the
@@ -249,7 +253,7 @@
  *
  * \return          The type of the message digest.
  */
-mbedtls_md_type_t mbedtls_md_get_type( const mbedtls_md_info_t *md_info );
+mbedtls_md_type_t mbedtls_md_get_type( mbedtls_md_handle_t md_info );
 
 /**
  * \brief           This function extracts the message-digest name from the
@@ -260,7 +264,7 @@
  *
  * \return          The name of the message digest.
  */
-const char *mbedtls_md_get_name( const mbedtls_md_info_t *md_info );
+const char *mbedtls_md_get_name( mbedtls_md_handle_t md_info );
 
 /**
  * \brief           This function starts a message-digest computation.
@@ -333,7 +337,7 @@
  * \return         #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                 failure.
  */
-int mbedtls_md( const mbedtls_md_info_t *md_info, const unsigned char *input, size_t ilen,
+int mbedtls_md( mbedtls_md_handle_t md_info, const unsigned char *input, size_t ilen,
         unsigned char *output );
 
 #if defined(MBEDTLS_FS_IO)
@@ -354,7 +358,7 @@
  *                 the file pointed by \p path.
  * \return         #MBEDTLS_ERR_MD_BAD_INPUT_DATA if \p md_info was NULL.
  */
-int mbedtls_md_file( const mbedtls_md_info_t *md_info, const char *path,
+int mbedtls_md_file( mbedtls_md_handle_t md_info, const char *path,
                      unsigned char *output );
 #endif /* MBEDTLS_FS_IO */
 
@@ -460,7 +464,7 @@
  * \return         #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                 failure.
  */
-int mbedtls_md_hmac( const mbedtls_md_info_t *md_info, const unsigned char *key, size_t keylen,
+int mbedtls_md_hmac( mbedtls_md_handle_t md_info, const unsigned char *key, size_t keylen,
                 const unsigned char *input, size_t ilen,
                 unsigned char *output );
 
diff --git a/library/ecdsa.c b/library/ecdsa.c
index 58e1a5f..94bb7f0 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -412,11 +412,14 @@
     mbedtls_hmac_drbg_context *p_rng = &rng_ctx;
     unsigned char data[2 * MBEDTLS_ECP_MAX_BYTES];
     size_t grp_len = ( grp->nbits + 7 ) / 8;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_mpi h;
 
-    if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL )
+    if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) ==
+        MBEDTLS_MD_INVALID_HANDLE )
+    {
         return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+    }
 
     mbedtls_mpi_init( &h );
     mbedtls_hmac_drbg_init( &rng_ctx );
diff --git a/library/ecjpake.c b/library/ecjpake.c
index b276514..ea28e6d 100644
--- a/library/ecjpake.c
+++ b/library/ecjpake.c
@@ -63,7 +63,7 @@
 {
     ECJPAKE_VALIDATE( ctx != NULL );
 
-    ctx->md_info = NULL;
+    ctx->md_info = MBEDTLS_MD_INVALID_HANDLE;
     mbedtls_ecp_group_init( &ctx->grp );
     ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
 
@@ -86,7 +86,7 @@
     if( ctx == NULL )
         return;
 
-    ctx->md_info = NULL;
+    ctx->md_info = MBEDTLS_MD_INVALID_HANDLE;
     mbedtls_ecp_group_free( &ctx->grp );
 
     mbedtls_ecp_point_free( &ctx->Xm1 );
@@ -119,8 +119,11 @@
 
     ctx->role = role;
 
-    if( ( ctx->md_info = mbedtls_md_info_from_type( hash ) ) == NULL )
+    if( ( ctx->md_info = mbedtls_md_info_from_type( hash ) ) ==
+        MBEDTLS_MD_INVALID_HANDLE )
+    {
         return( MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE );
+    }
 
     MBEDTLS_MPI_CHK( mbedtls_ecp_group_load( &ctx->grp, curve ) );
 
@@ -140,7 +143,7 @@
 {
     ECJPAKE_VALIDATE_RET( ctx != NULL );
 
-    if( ctx->md_info == NULL ||
+    if( ctx->md_info == MBEDTLS_MD_INVALID_HANDLE ||
         ctx->grp.id == MBEDTLS_ECP_DP_NONE ||
         ctx->s.p == NULL )
     {
@@ -190,7 +193,7 @@
 /*
  * Compute hash for ZKP (7.4.2.2.2.1)
  */
-static int ecjpake_hash( const mbedtls_md_info_t *md_info,
+static int ecjpake_hash( mbedtls_md_handle_t md_info,
                          const mbedtls_ecp_group *grp,
                          const int pf,
                          const mbedtls_ecp_point *G,
@@ -240,7 +243,7 @@
 /*
  * Parse a ECShnorrZKP (7.4.2.2.2) and verify it (7.4.2.3.3)
  */
-static int ecjpake_zkp_read( const mbedtls_md_info_t *md_info,
+static int ecjpake_zkp_read( mbedtls_md_handle_t md_info,
                              const mbedtls_ecp_group *grp,
                              const int pf,
                              const mbedtls_ecp_point *G,
@@ -312,7 +315,7 @@
 /*
  * Generate ZKP (7.4.2.3.2) and write it as ECSchnorrZKP (7.4.2.2.2)
  */
-static int ecjpake_zkp_write( const mbedtls_md_info_t *md_info,
+static int ecjpake_zkp_write( mbedtls_md_handle_t md_info,
                               const mbedtls_ecp_group *grp,
                               const int pf,
                               const mbedtls_ecp_point *G,
@@ -373,7 +376,7 @@
  * Parse a ECJPAKEKeyKP (7.4.2.2.1) and check proof
  * Output: verified public key X
  */
-static int ecjpake_kkp_read( const mbedtls_md_info_t *md_info,
+static int ecjpake_kkp_read( mbedtls_md_handle_t md_info,
                              const mbedtls_ecp_group *grp,
                              const int pf,
                              const mbedtls_ecp_point *G,
@@ -410,7 +413,7 @@
  * Generate an ECJPAKEKeyKP
  * Output: the serialized structure, plus private/public key pair
  */
-static int ecjpake_kkp_write( const mbedtls_md_info_t *md_info,
+static int ecjpake_kkp_write( mbedtls_md_handle_t md_info,
                               const mbedtls_ecp_group *grp,
                               const int pf,
                               const mbedtls_ecp_point *G,
@@ -447,7 +450,7 @@
  * Read a ECJPAKEKeyKPPairList (7.4.2.3) and check proofs
  * Ouputs: verified peer public keys Xa, Xb
  */
-static int ecjpake_kkpp_read( const mbedtls_md_info_t *md_info,
+static int ecjpake_kkpp_read( mbedtls_md_handle_t md_info,
                               const mbedtls_ecp_group *grp,
                               const int pf,
                               const mbedtls_ecp_point *G,
@@ -480,7 +483,7 @@
  * Generate a ECJPAKEKeyKPPairList
  * Outputs: the serialized structure, plus two private/public key pairs
  */
-static int ecjpake_kkpp_write( const mbedtls_md_info_t *md_info,
+static int ecjpake_kkpp_write( mbedtls_md_handle_t md_info,
                                const mbedtls_ecp_group *grp,
                                const int pf,
                                const mbedtls_ecp_point *G,
diff --git a/library/hkdf.c b/library/hkdf.c
index 82d8a42..d64dc4d 100644
--- a/library/hkdf.c
+++ b/library/hkdf.c
@@ -30,7 +30,7 @@
 #include "mbedtls/hkdf.h"
 #include "mbedtls/platform_util.h"
 
-int mbedtls_hkdf( const mbedtls_md_info_t *md, const unsigned char *salt,
+int mbedtls_hkdf( mbedtls_md_handle_t md, const unsigned char *salt,
                   size_t salt_len, const unsigned char *ikm, size_t ikm_len,
                   const unsigned char *info, size_t info_len,
                   unsigned char *okm, size_t okm_len )
@@ -51,7 +51,7 @@
     return( ret );
 }
 
-int mbedtls_hkdf_extract( const mbedtls_md_info_t *md,
+int mbedtls_hkdf_extract( mbedtls_md_handle_t md,
                           const unsigned char *salt, size_t salt_len,
                           const unsigned char *ikm, size_t ikm_len,
                           unsigned char *prk )
@@ -81,7 +81,7 @@
     return( mbedtls_md_hmac( md, salt, salt_len, ikm, ikm_len, prk ) );
 }
 
-int mbedtls_hkdf_expand( const mbedtls_md_info_t *md, const unsigned char *prk,
+int mbedtls_hkdf_expand( mbedtls_md_handle_t md, const unsigned char *prk,
                          size_t prk_len, const unsigned char *info,
                          size_t info_len, unsigned char *okm, size_t okm_len )
 {
diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index 34f1815..c9c541d 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -124,7 +124,7 @@
  * Simplified HMAC_DRBG initialisation (for use with deterministic ECDSA)
  */
 int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx,
-                        const mbedtls_md_info_t * md_info,
+                        mbedtls_md_handle_t md_info,
                         const unsigned char *data, size_t data_len )
 {
     int ret;
@@ -246,7 +246,7 @@
  * from the entropy source as suggested in 8.6.7.
  */
 int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx,
-                    const mbedtls_md_info_t * md_info,
+                    mbedtls_md_handle_t md_info,
                     int (*f_entropy)(void *, unsigned char *, size_t),
                     void *p_entropy,
                     const unsigned char *custom,
@@ -564,7 +564,7 @@
 {
     mbedtls_hmac_drbg_context ctx;
     unsigned char buf[OUTPUT_LEN];
-    const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 );
+    mbedtls_md_handle_t md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 );
 
     mbedtls_hmac_drbg_init( &ctx );
 
diff --git a/library/md.c b/library/md.c
index b3525be..d634606 100644
--- a/library/md.c
+++ b/library/md.c
@@ -94,7 +94,7 @@
     return( supported_digests );
 }
 
-const mbedtls_md_info_t *mbedtls_md_info_from_string( const char *md_name )
+mbedtls_md_handle_t mbedtls_md_info_from_string( const char *md_name )
 {
     if( NULL == md_name )
         return( NULL );
@@ -137,7 +137,7 @@
     return( NULL );
 }
 
-const mbedtls_md_info_t *mbedtls_md_info_from_type( mbedtls_md_type_t md_type )
+mbedtls_md_handle_t mbedtls_md_info_from_type( mbedtls_md_type_t md_type )
 {
     switch( md_type )
     {
@@ -187,7 +187,7 @@
 
 void mbedtls_md_free( mbedtls_md_context_t *ctx )
 {
-    if( ctx == NULL || ctx->md_info == NULL )
+    if( ctx == NULL || ctx->md_info == MBEDTLS_MD_INVALID_HANDLE )
         return;
 
     if( ctx->md_ctx != NULL )
@@ -206,8 +206,8 @@
 int mbedtls_md_clone( mbedtls_md_context_t *dst,
                       const mbedtls_md_context_t *src )
 {
-    if( dst == NULL || dst->md_info == NULL ||
-        src == NULL || src->md_info == NULL ||
+    if( dst == NULL || dst->md_info == MBEDTLS_MD_INVALID_HANDLE ||
+        src == NULL || src->md_info == MBEDTLS_MD_INVALID_HANDLE ||
         dst->md_info != src->md_info )
     {
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
@@ -219,15 +219,15 @@
 }
 
 #if ! defined(MBEDTLS_DEPRECATED_REMOVED)
-int mbedtls_md_init_ctx( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info )
+int mbedtls_md_init_ctx( mbedtls_md_context_t *ctx, mbedtls_md_handle_t md_info )
 {
     return mbedtls_md_setup( ctx, md_info, 1 );
 }
 #endif
 
-int mbedtls_md_setup( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info, int hmac )
+int mbedtls_md_setup( mbedtls_md_context_t *ctx, mbedtls_md_handle_t md_info, int hmac )
 {
-    if( md_info == NULL || ctx == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE || ctx == NULL )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     if( ( ctx->md_ctx = md_info->ctx_alloc_func() ) == NULL )
@@ -250,7 +250,7 @@
 
 int mbedtls_md_starts( mbedtls_md_context_t *ctx )
 {
-    if( ctx == NULL || ctx->md_info == NULL )
+    if( ctx == NULL || ctx->md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     return( ctx->md_info->starts_func( ctx->md_ctx ) );
@@ -258,7 +258,7 @@
 
 int mbedtls_md_update( mbedtls_md_context_t *ctx, const unsigned char *input, size_t ilen )
 {
-    if( ctx == NULL || ctx->md_info == NULL )
+    if( ctx == NULL || ctx->md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     return( ctx->md_info->update_func( ctx->md_ctx, input, ilen ) );
@@ -266,23 +266,23 @@
 
 int mbedtls_md_finish( mbedtls_md_context_t *ctx, unsigned char *output )
 {
-    if( ctx == NULL || ctx->md_info == NULL )
+    if( ctx == NULL || ctx->md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     return( ctx->md_info->finish_func( ctx->md_ctx, output ) );
 }
 
-int mbedtls_md( const mbedtls_md_info_t *md_info, const unsigned char *input, size_t ilen,
+int mbedtls_md( mbedtls_md_handle_t md_info, const unsigned char *input, size_t ilen,
             unsigned char *output )
 {
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     return( md_info->digest_func( input, ilen, output ) );
 }
 
 #if defined(MBEDTLS_FS_IO)
-int mbedtls_md_file( const mbedtls_md_info_t *md_info, const char *path, unsigned char *output )
+int mbedtls_md_file( mbedtls_md_handle_t md_info, const char *path, unsigned char *output )
 {
     int ret;
     FILE *f;
@@ -290,7 +290,7 @@
     mbedtls_md_context_t ctx;
     unsigned char buf[1024];
 
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     if( ( f = fopen( path, "rb" ) ) == NULL )
@@ -329,8 +329,12 @@
     unsigned char *ipad, *opad;
     size_t i;
 
-    if( ctx == NULL || ctx->md_info == NULL || ctx->hmac_ctx == NULL )
+    if( ctx == NULL                               ||
+        ctx->md_info == MBEDTLS_MD_INVALID_HANDLE ||
+        ctx->hmac_ctx == NULL )
+    {
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+    }
 
     if( keylen > (size_t) ctx->md_info->block_size )
     {
@@ -371,8 +375,12 @@
 
 int mbedtls_md_hmac_update( mbedtls_md_context_t *ctx, const unsigned char *input, size_t ilen )
 {
-    if( ctx == NULL || ctx->md_info == NULL || ctx->hmac_ctx == NULL )
+    if( ctx == NULL                               ||
+        ctx->md_info == MBEDTLS_MD_INVALID_HANDLE ||
+        ctx->hmac_ctx == NULL )
+    {
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+    }
 
     return( ctx->md_info->update_func( ctx->md_ctx, input, ilen ) );
 }
@@ -383,8 +391,12 @@
     unsigned char tmp[MBEDTLS_MD_MAX_SIZE];
     unsigned char *opad;
 
-    if( ctx == NULL || ctx->md_info == NULL || ctx->hmac_ctx == NULL )
+    if( ctx == NULL                               ||
+        ctx->md_info == MBEDTLS_MD_INVALID_HANDLE ||
+        ctx->hmac_ctx == NULL )
+    {
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+    }
 
     opad = (unsigned char *) ctx->hmac_ctx + ctx->md_info->block_size;
 
@@ -406,8 +418,12 @@
     int ret;
     unsigned char *ipad;
 
-    if( ctx == NULL || ctx->md_info == NULL || ctx->hmac_ctx == NULL )
+    if( ctx == NULL                               ||
+        ctx->md_info == MBEDTLS_MD_INVALID_HANDLE ||
+        ctx->hmac_ctx == NULL )
+    {
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+    }
 
     ipad = (unsigned char *) ctx->hmac_ctx;
 
@@ -417,7 +433,7 @@
                                        ctx->md_info->block_size ) );
 }
 
-int mbedtls_md_hmac( const mbedtls_md_info_t *md_info,
+int mbedtls_md_hmac( mbedtls_md_handle_t md_info,
                      const unsigned char *key, size_t keylen,
                      const unsigned char *input, size_t ilen,
                      unsigned char *output )
@@ -425,7 +441,7 @@
     mbedtls_md_context_t ctx;
     int ret;
 
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     mbedtls_md_init( &ctx );
@@ -448,31 +464,34 @@
 
 int mbedtls_md_process( mbedtls_md_context_t *ctx, const unsigned char *data )
 {
-    if( ctx == NULL || ctx->md_info == NULL )
+    if( ctx == NULL ||
+        ctx->md_info == MBEDTLS_MD_INVALID_HANDLE )
+    {
         return( MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+    }
 
     return( ctx->md_info->process_func( ctx->md_ctx, data ) );
 }
 
-unsigned char mbedtls_md_get_size( const mbedtls_md_info_t *md_info )
+unsigned char mbedtls_md_get_size( mbedtls_md_handle_t md_info )
 {
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( 0 );
 
     return md_info->size;
 }
 
-mbedtls_md_type_t mbedtls_md_get_type( const mbedtls_md_info_t *md_info )
+mbedtls_md_type_t mbedtls_md_get_type( mbedtls_md_handle_t md_info )
 {
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_MD_NONE );
 
     return md_info->type;
 }
 
-const char *mbedtls_md_get_name( const mbedtls_md_info_t *md_info )
+const char *mbedtls_md_get_name( mbedtls_md_handle_t md_info )
 {
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( NULL );
 
     return md_info->name;
diff --git a/library/pk.c b/library/pk.c
index 161a135..93c5764 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -205,13 +205,16 @@
  */
 static inline int pk_hashlen_helper( mbedtls_md_type_t md_alg, size_t *hash_len )
 {
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
 
     if( *hash_len != 0 )
         return( 0 );
 
-    if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL )
+    if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) ==
+        MBEDTLS_MD_INVALID_HANDLE )
+    {
         return( -1 );
+    }
 
     *hash_len = mbedtls_md_get_size( md_info );
     return( 0 );
diff --git a/library/pkcs11.c b/library/pkcs11.c
index 0ea6425..9ef5353 100644
--- a/library/pkcs11.c
+++ b/library/pkcs11.c
@@ -183,8 +183,8 @@
 
     if( md_alg != MBEDTLS_MD_NONE )
     {
-        const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg );
-        if( md_info == NULL )
+        mbedtls_md_handle_t md_info = mbedtls_md_info_from_type( md_alg );
+        if( md_info == MBEDTLS_MD_INVALID_HANDLE )
             return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
         if( mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size ) != 0 )
diff --git a/library/pkcs12.c b/library/pkcs12.c
index 7edf064..e16d0a9 100644
--- a/library/pkcs12.c
+++ b/library/pkcs12.c
@@ -261,7 +261,7 @@
 
     size_t hlen, use_len, v, i;
 
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_md_context_t md_ctx;
 
     // This version only allows max of 64 bytes of password or salt
@@ -269,7 +269,7 @@
         return( MBEDTLS_ERR_PKCS12_BAD_INPUT_DATA );
 
     md_info = mbedtls_md_info_from_type( md_type );
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE );
 
     mbedtls_md_init( &md_ctx );
diff --git a/library/pkcs5.c b/library/pkcs5.c
index 5013343..2717aaa 100644
--- a/library/pkcs5.c
+++ b/library/pkcs5.c
@@ -122,7 +122,7 @@
     mbedtls_md_type_t md_type = MBEDTLS_MD_SHA1;
     unsigned char key[32], iv[32];
     size_t olen = 0;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     const mbedtls_cipher_info_t *cipher_info;
     mbedtls_md_context_t md_ctx;
     mbedtls_cipher_type_t cipher_alg;
@@ -157,7 +157,7 @@
     }
 
     md_info = mbedtls_md_info_from_type( md_type );
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE );
 
     if( ( ret = mbedtls_asn1_get_alg( &p, end, &enc_scheme_oid,
@@ -356,14 +356,14 @@
 int mbedtls_pkcs5_self_test( int verbose )
 {
     mbedtls_md_context_t sha1_ctx;
-    const mbedtls_md_info_t *info_sha1;
+    mbedtls_md_handle_t info_sha1;
     int ret, i;
     unsigned char key[64];
 
     mbedtls_md_init( &sha1_ctx );
 
     info_sha1 = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 );
-    if( info_sha1 == NULL )
+    if( info_sha1 == MBEDTLS_MD_INVALID_HANDLE )
     {
         ret = 1;
         goto exit;
diff --git a/library/rsa.c b/library/rsa.c
index af1a878..2674c10 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -1128,7 +1128,7 @@
     int ret;
     unsigned char *p = output;
     unsigned int hlen;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_md_context_t md_ctx;
 
     RSA_VALIDATE_RET( ctx != NULL );
@@ -1145,7 +1145,7 @@
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id );
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     olen = ctx->len;
@@ -1326,7 +1326,7 @@
     unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
     unsigned char lhash[MBEDTLS_MD_MAX_SIZE];
     unsigned int hlen;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_md_context_t md_ctx;
 
     RSA_VALIDATE_RET( ctx != NULL );
@@ -1349,7 +1349,7 @@
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id );
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     hlen = mbedtls_md_get_size( md_info );
@@ -1767,7 +1767,7 @@
     size_t slen, min_slen, hlen, offset = 0;
     int ret;
     size_t msb;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_md_context_t md_ctx;
     RSA_VALIDATE_RET( ctx != NULL );
     RSA_VALIDATE_RET( mode == MBEDTLS_RSA_PRIVATE ||
@@ -1789,14 +1789,14 @@
     {
         /* Gather length of hash to sign */
         md_info = mbedtls_md_info_from_type( md_alg );
-        if( md_info == NULL )
+        if( md_info == MBEDTLS_MD_INVALID_HANDLE )
             return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
         hashlen = mbedtls_md_get_size( md_info );
     }
 
     md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id );
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     hlen = mbedtls_md_get_size( md_info );
@@ -1910,8 +1910,8 @@
     /* Are we signing hashed or raw data? */
     if( md_alg != MBEDTLS_MD_NONE )
     {
-        const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg );
-        if( md_info == NULL )
+        mbedtls_md_handle_t md_info = mbedtls_md_info_from_type( md_alg );
+        if( md_info == MBEDTLS_MD_INVALID_HANDLE )
             return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
         if( mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size ) != 0 )
@@ -2150,7 +2150,7 @@
     unsigned char zeros[8];
     unsigned int hlen;
     size_t observed_salt_len, msb;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_md_context_t md_ctx;
     unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
 
@@ -2186,14 +2186,14 @@
     {
         /* Gather length of hash to sign */
         md_info = mbedtls_md_info_from_type( md_alg );
-        if( md_info == NULL )
+        if( md_info == MBEDTLS_MD_INVALID_HANDLE )
             return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
         hashlen = mbedtls_md_get_size( md_info );
     }
 
     md_info = mbedtls_md_info_from_type( mgf1_hash_id );
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
         return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
 
     hlen = mbedtls_md_get_size( md_info );
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index e47c456..b17e33d 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -660,7 +660,7 @@
     const unsigned char *S1, *S2;
     unsigned char tmp[128];
     unsigned char h_i[20];
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_md_context_t md_ctx;
     int ret;
 
@@ -681,8 +681,11 @@
     /*
      * First compute P_md5(secret,label+random)[0..dlen]
      */
-    if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_MD5 ) ) == NULL )
+    if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_MD5 ) ) ==
+        MBEDTLS_MD_INVALID_HANDLE )
+    {
         return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
 
     if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 1 ) ) != 0 )
         return( ret );
@@ -712,8 +715,11 @@
     /*
      * XOR out with P_sha1(secret,label+random)[0..dlen]
      */
-    if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 ) ) == NULL )
+    if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 ) ) ==
+        MBEDTLS_MD_INVALID_HANDLE )
+    {
         return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
 
     if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 1 ) ) != 0 )
         return( ret );
@@ -763,14 +769,17 @@
     size_t i, j, k, md_len;
     unsigned char tmp[128];
     unsigned char h_i[MBEDTLS_MD_MAX_SIZE];
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_md_context_t md_ctx;
     int ret;
 
     mbedtls_md_init( &md_ctx );
 
-    if( ( md_info = mbedtls_md_info_from_type( md_type ) ) == NULL )
+    if( ( md_info = mbedtls_md_info_from_type( md_type ) ) ==
+        MBEDTLS_MD_INVALID_HANDLE )
+    {
         return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
 
     md_len = mbedtls_md_get_size( md_info );
 
@@ -1244,7 +1253,7 @@
     unsigned keylen;
     mbedtls_ssl_ciphersuite_handle_t ciphersuite_info;
     const mbedtls_cipher_info_t *cipher_info;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
 
 #if !defined(MBEDTLS_SSL_HW_RECORD_ACCEL) && \
     !defined(MBEDTLS_SSL_EXPORT_KEYS) && \
@@ -1293,7 +1302,7 @@
 
     md_info = mbedtls_md_info_from_type(
         mbedtls_ssl_suite_get_mac( ciphersuite_info ) );
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "mbedtls_md info for %d not found",
                        mbedtls_ssl_suite_get_mac( ciphersuite_info ) ) );
@@ -3368,7 +3377,8 @@
 
             memset( tmp, 0, sizeof( tmp ) );
 
-            switch( mbedtls_md_get_type( transform->md_ctx_dec.md_info ) )
+            switch( mbedtls_md_get_type(
+                        mbedtls_md_get_handle( &transform->md_ctx_dec ) ) )
             {
 #if defined(MBEDTLS_MD5_C) || defined(MBEDTLS_SHA1_C) || \
     defined(MBEDTLS_SHA256_C)
@@ -6890,13 +6900,16 @@
         ssl->session->peer_cert_digest;
     mbedtls_md_type_t const peer_cert_digest_type =
         ssl->session->peer_cert_digest_type;
-    mbedtls_md_info_t const * const digest_info =
+    mbedtls_md_handle_t digest_info =
         mbedtls_md_info_from_type( peer_cert_digest_type );
     unsigned char tmp_digest[MBEDTLS_SSL_PEER_CERT_DIGEST_MAX_LEN];
     size_t digest_len;
 
-    if( peer_cert_digest == NULL || digest_info == NULL )
+    if( peer_cert_digest == NULL ||
+        digest_info == MBEDTLS_MD_INVALID_HANDLE )
+    {
         return( -1 );
+    }
 
     digest_len = mbedtls_md_get_size( digest_info );
     if( digest_len > MBEDTLS_SSL_PEER_CERT_DIGEST_MAX_LEN )
@@ -10110,9 +10123,9 @@
 
     if( session->peer_cert_digest_len != 0 )
     {
-        const mbedtls_md_info_t *md_info =
+        mbedtls_md_handle_t md_info =
             mbedtls_md_info_from_type( session->peer_cert_digest_type );
-        if( md_info == NULL )
+        if( md_info == MBEDTLS_MD_INVALID_HANDLE )
             return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
         if( session->peer_cert_digest_len != mbedtls_md_get_size( md_info ) )
             return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
@@ -12484,7 +12497,7 @@
 {
     int ret = 0;
     mbedtls_md_context_t ctx;
-    const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg );
+    mbedtls_md_handle_t md_info = mbedtls_md_info_from_type( md_alg );
     *hashlen = mbedtls_md_get_size( md_info );
 
     mbedtls_md_init( &ctx );
diff --git a/library/x509.c b/library/x509.c
index 19cc64b..ec83017 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -1065,7 +1065,7 @@
     if( pk_alg == MBEDTLS_PK_RSASSA_PSS )
     {
         const mbedtls_pk_rsassa_pss_options *pss_opts;
-        const mbedtls_md_info_t *md_info, *mgf_md_info;
+        mbedtls_md_handle_t md_info, mgf_md_info;
 
         pss_opts = (const mbedtls_pk_rsassa_pss_options *) sig_opts;
 
diff --git a/library/x509_crt.c b/library/x509_crt.c
index 0089ef2..2960638 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -2088,7 +2088,7 @@
 static int x509_crt_get_sig_info( mbedtls_x509_crt_frame const *frame,
                                   mbedtls_x509_crt_sig_info *info )
 {
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
 
     md_info = mbedtls_md_info_from_type( frame->sig_md );
     if( mbedtls_md( md_info, frame->tbs.p, frame->tbs.len,
@@ -2705,7 +2705,7 @@
     int ret;
     int flags = 0;
     unsigned char hash[MBEDTLS_MD_MAX_SIZE];
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_x509_buf_raw ca_subject;
     mbedtls_pk_context *pk;
     int can_sign;
diff --git a/programs/aes/crypt_and_hash.c b/programs/aes/crypt_and_hash.c
index a5acf5b..8d671ab 100644
--- a/programs/aes/crypt_and_hash.c
+++ b/programs/aes/crypt_and_hash.c
@@ -100,7 +100,7 @@
     unsigned char diff;
 
     const mbedtls_cipher_info_t *cipher_info;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_cipher_context_t cipher_ctx;
     mbedtls_md_context_t md_ctx;
 #if defined(_WIN32_WCE)
@@ -192,7 +192,7 @@
     }
 
     md_info = mbedtls_md_info_from_string( argv[5] );
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
     {
         mbedtls_fprintf( stderr, "Message Digest '%s' not found\n", argv[5] );
         goto exit;
diff --git a/programs/hash/generic_sum.c b/programs/hash/generic_sum.c
index 709a149..ed5357f 100644
--- a/programs/hash/generic_sum.c
+++ b/programs/hash/generic_sum.c
@@ -53,7 +53,7 @@
 #else
 
 
-static int generic_wrapper( const mbedtls_md_info_t *md_info, char *filename, unsigned char *sum )
+static int generic_wrapper( mbedtls_md_handle_t md_info, char *filename, unsigned char *sum )
 {
     int ret = mbedtls_md_file( md_info, filename, sum );
 
@@ -66,7 +66,7 @@
     return( ret );
 }
 
-static int generic_print( const mbedtls_md_info_t *md_info, char *filename )
+static int generic_print( mbedtls_md_handle_t md_info, char *filename )
 {
     int i;
     unsigned char sum[MBEDTLS_MD_MAX_SIZE];
@@ -81,7 +81,7 @@
     return( 0 );
 }
 
-static int generic_check( const mbedtls_md_info_t *md_info, char *filename )
+static int generic_check( mbedtls_md_handle_t md_info, char *filename )
 {
     int i;
     size_t n;
@@ -177,7 +177,7 @@
 {
     int ret = 1, i;
     int exit_code = MBEDTLS_EXIT_FAILURE;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_md_context_t md_ctx;
 
     mbedtls_md_init( &md_ctx );
@@ -210,7 +210,7 @@
      * Read the MD from the command line
      */
     md_info = mbedtls_md_info_from_string( argv[1] );
-    if( md_info == NULL )
+    if( md_info == MBEDTLS_MD_INVALID_HANDLE )
     {
         mbedtls_fprintf( stderr, "Message Digest '%s' not found\n", argv[1] );
         return( exit_code );
diff --git a/programs/test/benchmark.c b/programs/test/benchmark.c
index 2b86566..88e3290 100644
--- a/programs/test/benchmark.c
+++ b/programs/test/benchmark.c
@@ -693,13 +693,16 @@
     if( todo.hmac_drbg )
     {
         mbedtls_hmac_drbg_context hmac_drbg;
-        const mbedtls_md_info_t *md_info;
+        mbedtls_md_handle_t md_info;
 
         mbedtls_hmac_drbg_init( &hmac_drbg );
 
 #if defined(MBEDTLS_SHA1_C)
-        if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 ) ) == NULL )
+        if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 ) ) ==
+            MBEDTLS_MD_INVALID_HANDLE )
+        {
             mbedtls_exit(1);
+        }
 
         if( mbedtls_hmac_drbg_seed( &hmac_drbg, md_info, myrand, NULL, NULL, 0 ) != 0 )
             mbedtls_exit(1);
@@ -715,8 +718,11 @@
 #endif
 
 #if defined(MBEDTLS_SHA256_C)
-        if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ) ) == NULL )
+        if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ) ) ==
+            MBEDTLS_MD_INVALID_HANDLE )
+        {
             mbedtls_exit(1);
+        }
 
         if( mbedtls_hmac_drbg_seed( &hmac_drbg, md_info, myrand, NULL, NULL, 0 ) != 0 )
             mbedtls_exit(1);
diff --git a/tests/suites/test_suite_ecdsa.function b/tests/suites/test_suite_ecdsa.function
index 22d92b6..fa77dfa 100644
--- a/tests/suites/test_suite_ecdsa.function
+++ b/tests/suites/test_suite_ecdsa.function
@@ -307,7 +307,7 @@
     mbedtls_mpi d, r, s, r_check, s_check;
     unsigned char hash[MBEDTLS_MD_MAX_SIZE];
     size_t hlen;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
 
     mbedtls_ecp_group_init( &grp );
     mbedtls_mpi_init( &d ); mbedtls_mpi_init( &r ); mbedtls_mpi_init( &s );
@@ -320,7 +320,7 @@
     TEST_ASSERT( mbedtls_mpi_read_string( &s_check, 16, s_str ) == 0 );
 
     md_info = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
     hlen = mbedtls_md_get_size( md_info );
     TEST_ASSERT( mbedtls_md( md_info, (const unsigned char *) msg,
                  strlen( msg ), hash ) == 0 );
@@ -476,7 +476,7 @@
     unsigned char sig[MBEDTLS_ECDSA_MAX_LEN];
     unsigned char sig_check[MBEDTLS_ECDSA_MAX_LEN];
     size_t hlen, slen, slen_check;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
 
     mbedtls_ecdsa_restart_init( &rs_ctx );
     mbedtls_ecdsa_init( &ctx );
@@ -489,7 +489,7 @@
     slen_check = unhexify( sig_check, sig_str );
 
     md_info = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     hlen = mbedtls_md_get_size( md_info );
     mbedtls_md( md_info, (const unsigned char *) msg, strlen( msg ), hash );
diff --git a/tests/suites/test_suite_hkdf.function b/tests/suites/test_suite_hkdf.function
index 3e87207..7e83b57 100644
--- a/tests/suites/test_suite_hkdf.function
+++ b/tests/suites/test_suite_hkdf.function
@@ -25,8 +25,8 @@
      */
     unsigned char okm_hex[257] = { '\0' };
 
-    const mbedtls_md_info_t *md = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md != NULL );
+    mbedtls_md_handle_t md = mbedtls_md_info_from_type( md_alg );
+    TEST_ASSERT( md != MBEDTLS_MD_INVALID_HANDLE );
 
     ikm_len = unhexify( ikm, hex_ikm_string );
     salt_len = unhexify( salt, hex_salt_string );
@@ -54,8 +54,8 @@
     unsigned char *output_prk = NULL;
     size_t ikm_len, salt_len, prk_len, output_prk_len;
 
-    const mbedtls_md_info_t *md = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md != NULL );
+    mbedtls_md_handle_t md = mbedtls_md_info_from_type( md_alg );
+    TEST_ASSERT( md != MBEDTLS_MD_INVALID_HANDLE );
 
     output_prk_len = mbedtls_md_get_size( md );
     output_prk = mbedtls_calloc( 1, output_prk_len );
@@ -90,8 +90,8 @@
     unsigned char *output_okm = NULL;
     size_t info_len, prk_len, okm_len;
 
-    const mbedtls_md_info_t *md = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md != NULL );
+    mbedtls_md_handle_t md = mbedtls_md_info_from_type( md_alg );
+    TEST_ASSERT( md != MBEDTLS_MD_INVALID_HANDLE );
 
     output_okm = mbedtls_calloc( OKM_LEN, 1 );
 
diff --git a/tests/suites/test_suite_hmac_drbg.function b/tests/suites/test_suite_hmac_drbg.function
index 13bc400..da280db 100644
--- a/tests/suites/test_suite_hmac_drbg.function
+++ b/tests/suites/test_suite_hmac_drbg.function
@@ -34,7 +34,7 @@
 {
     unsigned char out[16];
     unsigned char buf[1024];
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_hmac_drbg_context ctx;
     entropy_ctx entropy;
     size_t last_len, i, reps = 10;
@@ -47,7 +47,7 @@
     entropy.p = buf;
 
     md_info = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     /* Init must use entropy */
     last_len = entropy.len;
@@ -112,13 +112,13 @@
 /* BEGIN_CASE depends_on:MBEDTLS_FS_IO */
 void hmac_drbg_seed_file( int md_alg, char * path, int ret )
 {
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_hmac_drbg_context ctx;
 
     mbedtls_hmac_drbg_init( &ctx );
 
     md_info = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     TEST_ASSERT( mbedtls_hmac_drbg_seed( &ctx, md_info, rnd_std_rand, NULL,
                                  NULL, 0 ) == 0 );
@@ -136,7 +136,7 @@
 {
     unsigned char out[16];
     unsigned char buf[100];
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_hmac_drbg_context ctx;
     size_t i;
 
@@ -145,7 +145,7 @@
     memset( out, 0, sizeof( out ) );
 
     md_info = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
     TEST_ASSERT( mbedtls_hmac_drbg_seed_buf( &ctx, md_info, buf, sizeof( buf ) ) == 0 );
 
     /* Make sure it never tries to reseed (would segfault otherwise) */
@@ -168,7 +168,7 @@
     unsigned char data[1024];
     unsigned char my_output[512];
     entropy_ctx p_entropy;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_hmac_drbg_context ctx;
 
     mbedtls_hmac_drbg_init( &ctx );
@@ -177,7 +177,7 @@
     p_entropy.len = entropy->len;
 
     md_info = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     /* Test the simplified buffer-based variant */
     memcpy( data, entropy->x, p_entropy.len );
@@ -215,7 +215,7 @@
 {
     unsigned char my_output[512];
     entropy_ctx p_entropy;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_hmac_drbg_context ctx;
 
     mbedtls_hmac_drbg_init( &ctx );
@@ -224,7 +224,7 @@
     p_entropy.len = entropy->len;
 
     md_info = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     TEST_ASSERT( mbedtls_hmac_drbg_seed( &ctx, md_info, mbedtls_test_entropy_func, &p_entropy,
                                  custom->x, custom->len ) == 0 );
@@ -247,7 +247,7 @@
 {
     unsigned char my_output[512];
     entropy_ctx p_entropy;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     mbedtls_hmac_drbg_context ctx;
 
     mbedtls_hmac_drbg_init( &ctx );
@@ -256,7 +256,7 @@
     p_entropy.len = entropy->len;
 
     md_info = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     TEST_ASSERT( mbedtls_hmac_drbg_seed( &ctx, md_info, mbedtls_test_entropy_func, &p_entropy,
                                  custom->x, custom->len ) == 0 );
diff --git a/tests/suites/test_suite_md.function b/tests/suites/test_suite_md.function
index 11cf88a..515a28c 100644
--- a/tests/suites/test_suite_md.function
+++ b/tests/suites/test_suite_md.function
@@ -11,7 +11,7 @@
 void mbedtls_md_process(  )
 {
     const int *md_type_ptr;
-    const mbedtls_md_info_t *info;
+    mbedtls_md_handle_t info;
     mbedtls_md_context_t ctx;
     unsigned char buf[150];
 
@@ -28,7 +28,7 @@
     for( md_type_ptr = mbedtls_md_list(); *md_type_ptr != 0; md_type_ptr++ )
     {
         info = mbedtls_md_info_from_type( *md_type_ptr );
-        TEST_ASSERT( info != NULL );
+        TEST_ASSERT( info != MBEDTLS_MD_INVALID_HANDLE );
         TEST_ASSERT( mbedtls_md_setup( &ctx, info, 0 ) == 0 );
         TEST_ASSERT( mbedtls_md_process( &ctx, buf ) == 0 );
         mbedtls_md_free( &ctx );
@@ -43,18 +43,22 @@
 void md_null_args(  )
 {
     mbedtls_md_context_t ctx;
-    const mbedtls_md_info_t *info = mbedtls_md_info_from_type( *( mbedtls_md_list() ) );
+    mbedtls_md_handle_t info = mbedtls_md_info_from_type( *( mbedtls_md_list() ) );
     unsigned char buf[1] = { 0 };
 
     mbedtls_md_init( &ctx );
 
-    TEST_ASSERT( mbedtls_md_get_size( NULL ) == 0 );
-    TEST_ASSERT( mbedtls_md_get_type( NULL ) == MBEDTLS_MD_NONE );
-    TEST_ASSERT( mbedtls_md_get_name( NULL ) == NULL );
+    TEST_ASSERT( mbedtls_md_get_size( MBEDTLS_MD_INVALID_HANDLE )
+                 == 0 );
+    TEST_ASSERT( mbedtls_md_get_type( MBEDTLS_MD_INVALID_HANDLE )
+                 == MBEDTLS_MD_NONE );
+    TEST_ASSERT( mbedtls_md_get_name( MBEDTLS_MD_INVALID_HANDLE )
+                 == NULL );
 
-    TEST_ASSERT( mbedtls_md_info_from_string( NULL ) == NULL );
+    TEST_ASSERT( mbedtls_md_info_from_string( NULL ) == MBEDTLS_MD_INVALID_HANDLE );
 
-    TEST_ASSERT( mbedtls_md_setup( &ctx, NULL, 0 ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+    TEST_ASSERT( mbedtls_md_setup( &ctx, MBEDTLS_MD_INVALID_HANDLE, 0 )
+                 == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
     TEST_ASSERT( mbedtls_md_setup( NULL, info, 0 ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     TEST_ASSERT( mbedtls_md_starts( NULL ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
@@ -66,10 +70,12 @@
     TEST_ASSERT( mbedtls_md_finish( NULL, buf ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
     TEST_ASSERT( mbedtls_md_finish( &ctx, buf ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
-    TEST_ASSERT( mbedtls_md( NULL, buf, 1, buf ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+    TEST_ASSERT( mbedtls_md( MBEDTLS_MD_INVALID_HANDLE,
+                             buf, 1, buf ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
 #if defined(MBEDTLS_FS_IO)
-    TEST_ASSERT( mbedtls_md_file( NULL, "", buf ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
+    TEST_ASSERT( mbedtls_md_file( MBEDTLS_MD_INVALID_HANDLE,
+                                  "", buf ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 #endif
 
     TEST_ASSERT( mbedtls_md_hmac_starts( NULL, buf, 1 )
@@ -90,27 +96,29 @@
     TEST_ASSERT( mbedtls_md_hmac_reset( NULL ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
     TEST_ASSERT( mbedtls_md_hmac_reset( &ctx ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
-    TEST_ASSERT( mbedtls_md_hmac( NULL, buf, 1, buf, 1, buf )
+    TEST_ASSERT( mbedtls_md_hmac( MBEDTLS_MD_INVALID_HANDLE, buf, 1, buf, 1, buf )
                  == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     TEST_ASSERT( mbedtls_md_process( NULL, buf ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
     TEST_ASSERT( mbedtls_md_process( &ctx, buf ) == MBEDTLS_ERR_MD_BAD_INPUT_DATA );
 
     /* Ok, this is not NULL arg but NULL return... */
-    TEST_ASSERT( mbedtls_md_info_from_type( MBEDTLS_MD_NONE ) == NULL );
-    TEST_ASSERT( mbedtls_md_info_from_string( "no such md" ) == NULL );
+    TEST_ASSERT( mbedtls_md_info_from_type( MBEDTLS_MD_NONE ) ==
+                 MBEDTLS_MD_INVALID_HANDLE );
+    TEST_ASSERT( mbedtls_md_info_from_string( "no such md" ) ==
+                 MBEDTLS_MD_INVALID_HANDLE );
 }
 /* END_CASE */
 
 /* BEGIN_CASE */
 void md_info( int md_type, char * md_name, int md_size )
 {
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
     const int *md_type_ptr;
     int found;
 
     md_info = mbedtls_md_info_from_type( md_type );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
     TEST_ASSERT( md_info == mbedtls_md_info_from_string( md_name ) );
 
     TEST_ASSERT( mbedtls_md_get_type( md_info ) == (mbedtls_md_type_t) md_type );
@@ -132,7 +140,7 @@
     char md_name[100];
     unsigned char src_str[1000];
     unsigned char output[100];
-    const mbedtls_md_info_t *md_info = NULL;
+    mbedtls_md_handle_t md_info = MBEDTLS_MD_INVALID_HANDLE;
 
     memset( md_name, 0x00, 100 );
     memset( src_str, 0x00, 1000 );
@@ -141,7 +149,7 @@
     strncpy( (char *) src_str, text_src_string, sizeof( src_str ) - 1 );
     strncpy( (char *) md_name, text_md_name, sizeof( md_name ) - 1 );
     md_info = mbedtls_md_info_from_string(md_name);
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     TEST_ASSERT ( 0 == mbedtls_md( md_info, src_str, strlen( (char *) src_str ), output ) );
 
@@ -155,14 +163,14 @@
 {
     char md_name[100];
     unsigned char output[100];
-    const mbedtls_md_info_t *md_info = NULL;
+    mbedtls_md_handle_t md_info = MBEDTLS_MD_INVALID_HANDLE;
 
     memset( md_name, 0x00, 100 );
     memset( output, 0x00, 100 );
 
     strncpy( (char *) md_name, text_md_name, sizeof( md_name ) - 1 );
     md_info = mbedtls_md_info_from_string( md_name );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     TEST_ASSERT ( 0 == mbedtls_md( md_info, src_str->x, src_str->len, output ) );
 
@@ -181,7 +189,7 @@
     unsigned char output[100];
     int halfway, len;
 
-    const mbedtls_md_info_t *md_info = NULL;
+    mbedtls_md_handle_t md_info = MBEDTLS_MD_INVALID_HANDLE;
     mbedtls_md_context_t ctx, ctx_copy;
 
     mbedtls_md_init( &ctx );
@@ -197,7 +205,7 @@
     halfway = len / 2;
 
     md_info = mbedtls_md_info_from_string(md_name);
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
     TEST_ASSERT ( 0 == mbedtls_md_setup( &ctx, md_info, 0 ) );
     TEST_ASSERT ( 0 == mbedtls_md_setup( &ctx_copy, md_info, 0 ) );
 
@@ -230,7 +238,7 @@
 {
     char md_name[100];
     unsigned char output[100];
-    const mbedtls_md_info_t *md_info = NULL;
+    mbedtls_md_handle_t md_info = MBEDTLS_MD_INVALID_HANDLE;
     mbedtls_md_context_t ctx, ctx_copy;
     int halfway;
 
@@ -242,7 +250,7 @@
 
     strncpy( (char *) md_name, text_md_name, sizeof( md_name ) - 1 );
     md_info = mbedtls_md_info_from_string(md_name);
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
     TEST_ASSERT ( 0 == mbedtls_md_setup( &ctx, md_info, 0 ) );
     TEST_ASSERT ( 0 == mbedtls_md_setup( &ctx_copy, md_info, 0 ) );
 
@@ -277,14 +285,14 @@
 {
     char md_name[100];
     unsigned char output[100];
-    const mbedtls_md_info_t *md_info = NULL;
+    mbedtls_md_handle_t md_info = MBEDTLS_MD_INVALID_HANDLE;
 
     memset( md_name, 0x00, 100 );
     memset( output, 0x00, 100 );
 
     strncpy( (char *) md_name, text_md_name, sizeof( md_name ) - 1 );
     md_info = mbedtls_md_info_from_string( md_name );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
 
     TEST_ASSERT ( mbedtls_md_hmac( md_info, key_str->x, key_str->len, src_str->x, src_str->len, output ) == 0 );
@@ -299,7 +307,7 @@
 {
     char md_name[100];
     unsigned char output[100];
-    const mbedtls_md_info_t *md_info = NULL;
+    mbedtls_md_handle_t md_info = MBEDTLS_MD_INVALID_HANDLE;
     mbedtls_md_context_t ctx;
     int halfway;
 
@@ -310,7 +318,7 @@
 
     strncpy( (char *) md_name, text_md_name, sizeof( md_name ) - 1 );
     md_info = mbedtls_md_info_from_string( md_name );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
     TEST_ASSERT ( 0 == mbedtls_md_setup( &ctx, md_info, 1 ) );
 
     halfway = src_str->len / 2;
@@ -344,14 +352,14 @@
 {
     char md_name[100];
     unsigned char output[100];
-    const mbedtls_md_info_t *md_info = NULL;
+    mbedtls_md_handle_t md_info = MBEDTLS_MD_INVALID_HANDLE;
 
     memset( md_name, 0x00, 100 );
     memset( output, 0x00, 100 );
 
     strncpy( (char *) md_name, text_md_name, sizeof( md_name ) - 1 );
     md_info = mbedtls_md_info_from_string( md_name );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     TEST_ASSERT( mbedtls_md_file( md_info, filename, output ) == 0 );
 
diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function
index 8b95bab..fc917d0 100644
--- a/tests/suites/test_suite_pk.function
+++ b/tests/suites/test_suite_pk.function
@@ -593,7 +593,7 @@
     TEST_ASSERT( mbedtls_mpi_read_string( &rsa->E, radix_E, input_E ) == 0 );
 
 
-    if( mbedtls_md_info_from_type( digest ) != NULL )
+    if( mbedtls_md_info_from_type( digest ) != MBEDTLS_MD_INVALID_HANDLE )
         TEST_ASSERT( mbedtls_md( mbedtls_md_info_from_type( digest ), message_str->x, message_str->len, hash_result ) == 0 );
 
     TEST_ASSERT( mbedtls_pk_verify( &pk, digest, hash_result, 0,
@@ -709,7 +709,7 @@
     unsigned char sig[MBEDTLS_ECDSA_MAX_LEN];
     unsigned char sig_check[MBEDTLS_ECDSA_MAX_LEN];
     size_t hlen, slen, slen_check;
-    const mbedtls_md_info_t *md_info;
+    mbedtls_md_handle_t md_info;
 
     mbedtls_pk_restart_init( &rs_ctx );
     mbedtls_pk_init( &prv );
@@ -729,7 +729,7 @@
     slen_check = unhexify( sig_check, sig_str );
 
     md_info = mbedtls_md_info_from_type( md_alg );
-    TEST_ASSERT( md_info != NULL );
+    TEST_ASSERT( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
     hlen = mbedtls_md_get_size( md_info );
     mbedtls_md( md_info, (const unsigned char *) msg, strlen( msg ), hash );
diff --git a/tests/suites/test_suite_pkcs1_v15.function b/tests/suites/test_suite_pkcs1_v15.function
index 0723623..58c25bf 100644
--- a/tests/suites/test_suite_pkcs1_v15.function
+++ b/tests/suites/test_suite_pkcs1_v15.function
@@ -275,8 +275,10 @@
     TEST_ASSERT( mbedtls_rsa_check_privkey( &ctx ) == 0 );
 
 
-    if( mbedtls_md_info_from_type( digest ) != NULL )
+    if( mbedtls_md_info_from_type( digest ) != MBEDTLS_MD_INVALID_HANDLE )
+    {
         TEST_ASSERT( mbedtls_md( mbedtls_md_info_from_type( digest ), message_str->x, message_str->len, hash_result ) == 0 );
+    }
 
     TEST_ASSERT( mbedtls_rsa_pkcs1_sign( &ctx, &rnd_buffer_rand, &info, MBEDTLS_RSA_PRIVATE, digest, 0, hash_result, output ) == result );
     if( result == 0 )
@@ -313,9 +315,10 @@
     TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( ( mod + 7 ) / 8 ) );
     TEST_ASSERT( mbedtls_rsa_check_pubkey( &ctx ) == 0 );
 
-
-    if( mbedtls_md_info_from_type( digest ) != NULL )
+    if( mbedtls_md_info_from_type( digest ) != MBEDTLS_MD_INVALID_HANDLE )
+    {
         TEST_ASSERT( mbedtls_md( mbedtls_md_info_from_type( digest ), message_str->x, message_str->len, hash_result ) == 0 );
+    }
 
     TEST_ASSERT( mbedtls_rsa_pkcs1_verify( &ctx, NULL, NULL, MBEDTLS_RSA_PUBLIC, digest, 0, hash_result, result_str->x ) == result );
 
diff --git a/tests/suites/test_suite_pkcs1_v21.function b/tests/suites/test_suite_pkcs1_v21.function
index 99be08a..a9635e1 100644
--- a/tests/suites/test_suite_pkcs1_v21.function
+++ b/tests/suites/test_suite_pkcs1_v21.function
@@ -128,8 +128,10 @@
     TEST_ASSERT( mbedtls_rsa_check_privkey( &ctx ) == 0 );
 
 
-    if( mbedtls_md_info_from_type( digest ) != NULL )
+    if( mbedtls_md_info_from_type( digest ) != MBEDTLS_MD_INVALID_HANDLE )
+    {
         TEST_ASSERT( mbedtls_md( mbedtls_md_info_from_type( digest ), message_str->x, message_str->len, hash_result ) == 0 );
+    }
 
     TEST_ASSERT( mbedtls_rsa_pkcs1_sign( &ctx, &rnd_buffer_rand, &info, MBEDTLS_RSA_PRIVATE,
                                          digest, 0, hash_result, output ) == result );
@@ -169,8 +171,10 @@
     TEST_ASSERT( mbedtls_rsa_check_pubkey( &ctx ) == 0 );
 
 
-    if( mbedtls_md_info_from_type( digest ) != NULL )
+    if( mbedtls_md_info_from_type( digest ) != MBEDTLS_MD_INVALID_HANDLE )
+    {
         TEST_ASSERT( mbedtls_md( mbedtls_md_info_from_type( digest ), message_str->x, message_str->len, hash_result ) == 0 );
+    }
 
     TEST_ASSERT( mbedtls_rsa_pkcs1_verify( &ctx, NULL, NULL, MBEDTLS_RSA_PUBLIC, digest, 0, hash_result, result_str->x ) == result );
 
diff --git a/tests/suites/test_suite_pkcs5.function b/tests/suites/test_suite_pkcs5.function
index 26f1d33..a8f0523 100644
--- a/tests/suites/test_suite_pkcs5.function
+++ b/tests/suites/test_suite_pkcs5.function
@@ -12,14 +12,14 @@
                   int it_cnt, int key_len, data_t * result_key_string )
 {
     mbedtls_md_context_t ctx;
-    const mbedtls_md_info_t *info;
+    mbedtls_md_handle_t info;
 
     unsigned char key[100];
 
     mbedtls_md_init( &ctx );
 
     info = mbedtls_md_info_from_type( hash );
-    TEST_ASSERT( info != NULL );
+    TEST_ASSERT( info != MBEDTLS_MD_INVALID_HANDLE );
     TEST_ASSERT( mbedtls_md_setup( &ctx, info, 1 ) == 0 );
     TEST_ASSERT( mbedtls_pkcs5_pbkdf2_hmac( &ctx, pw_str->x, pw_str->len, salt_str->x, salt_str->len,
                                      it_cnt, key_len, key ) == 0 );
diff --git a/tests/suites/test_suite_rsa.function b/tests/suites/test_suite_rsa.function
index f2a9b98..4d22c9b 100644
--- a/tests/suites/test_suite_rsa.function
+++ b/tests/suites/test_suite_rsa.function
@@ -497,8 +497,10 @@
     TEST_ASSERT( mbedtls_rsa_check_privkey( &ctx ) == 0 );
 
 
-    if( mbedtls_md_info_from_type( digest ) != NULL )
+    if( mbedtls_md_info_from_type( digest ) != MBEDTLS_MD_INVALID_HANDLE )
+    {
         TEST_ASSERT( mbedtls_md( mbedtls_md_info_from_type( digest ), message_str->x, message_str->len, hash_result ) == 0 );
+    }
 
     TEST_ASSERT( mbedtls_rsa_pkcs1_sign( &ctx, &rnd_pseudo_rand, &rnd_info,
                                          MBEDTLS_RSA_PRIVATE, digest, 0,
@@ -538,8 +540,10 @@
     TEST_ASSERT( mbedtls_rsa_check_pubkey( &ctx ) == 0 );
 
 
-    if( mbedtls_md_info_from_type( digest ) != NULL )
+    if( mbedtls_md_info_from_type( digest ) != MBEDTLS_MD_INVALID_HANDLE )
+    {
         TEST_ASSERT( mbedtls_md( mbedtls_md_info_from_type( digest ), message_str->x, message_str->len, hash_result ) == 0 );
+    }
 
     TEST_ASSERT( mbedtls_rsa_pkcs1_verify( &ctx, NULL, NULL, MBEDTLS_RSA_PUBLIC, digest, 0, hash_result, result_str->x ) == result );
 
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index b177779..80f5f16 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -102,12 +102,12 @@
     if( cipher_info->mode == MBEDTLS_MODE_CBC ||
         cipher_info->mode == MBEDTLS_MODE_STREAM )
     {
-        mbedtls_md_info_t const *md_info;
+        mbedtls_md_handle_t md_info;
         unsigned char *md0, *md1;
 
         /* Pick hash */
         md_info = mbedtls_md_info_from_type( hash_id );
-        CHK( md_info != NULL );
+        CHK( md_info != MBEDTLS_MD_INVALID_HANDLE );
 
         /* Pick hash keys */
         maclen = mbedtls_md_get_size( md_info );