diff --git a/ChangeLog.d/check-return.txt b/ChangeLog.d/check-return.txt
index 045b180..7d905da 100644
--- a/ChangeLog.d/check-return.txt
+++ b/ChangeLog.d/check-return.txt
@@ -5,6 +5,8 @@
      This does not concern the implementation provided with Mbed TLS,
      where this function cannot fail, or full-module replacements with
      MBEDTLS_AES_ALT or MBEDTLS_DES_ALT. Reported by Armelle Duboc in #1092.
+   * Some failures of HMAC operations were ignored. These failures could only
+     happen with an alternative implementation of the underlying hash module.
 
 Features
    * Warn if errors from certain functions are ignored. This is currently
@@ -13,5 +15,5 @@
      (where supported) for critical functions where ignoring the return
      value is almost always a bug. Enable the new configuration option
      MBEDTLS_CHECK_RETURN_WARNING to get warnings for other functions. This
-     is currently implemented in the AES and DES modules, and will be extended
-     to other modules in the future.
+     is currently implemented in the AES, DES and md modules, and will be
+     extended to other modules in the future.
diff --git a/include/mbedtls/md.h b/include/mbedtls/md.h
index fa2b152..2b668f5 100644
--- a/include/mbedtls/md.h
+++ b/include/mbedtls/md.h
@@ -29,6 +29,7 @@
 #include <stddef.h>
 
 #include "mbedtls/build_info.h"
+#include "mbedtls/platform_util.h"
 
 /** The selected feature is not available. */
 #define MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE                -0x5080
@@ -181,6 +182,7 @@
  *                  failure.
  * \return          #MBEDTLS_ERR_MD_ALLOC_FAILED on memory-allocation failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_setup( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info, int hmac );
 
 /**
@@ -202,6 +204,7 @@
  * \return          \c 0 on success.
  * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_clone( mbedtls_md_context_t *dst,
                       const mbedtls_md_context_t *src );
 
@@ -251,6 +254,7 @@
  * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                  failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_starts( mbedtls_md_context_t *ctx );
 
 /**
@@ -269,6 +273,7 @@
  * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                  failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_update( mbedtls_md_context_t *ctx, const unsigned char *input, size_t ilen );
 
 /**
@@ -289,6 +294,7 @@
  * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                  failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_finish( mbedtls_md_context_t *ctx, unsigned char *output );
 
 /**
@@ -309,6 +315,7 @@
  * \return         #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                 failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md( const mbedtls_md_info_t *md_info, const unsigned char *input, size_t ilen,
         unsigned char *output );
 
@@ -330,6 +337,7 @@
  *                 the file pointed by \p path.
  * \return         #MBEDTLS_ERR_MD_BAD_INPUT_DATA if \p md_info was NULL.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_file( const mbedtls_md_info_t *md_info, const char *path,
                      unsigned char *output );
 #endif /* MBEDTLS_FS_IO */
@@ -352,6 +360,7 @@
  * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                  failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_hmac_starts( mbedtls_md_context_t *ctx, const unsigned char *key,
                     size_t keylen );
 
@@ -374,6 +383,7 @@
  * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                  failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_hmac_update( mbedtls_md_context_t *ctx, const unsigned char *input,
                     size_t ilen );
 
@@ -395,6 +405,7 @@
  * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                  failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_hmac_finish( mbedtls_md_context_t *ctx, unsigned char *output);
 
 /**
@@ -412,6 +423,7 @@
  * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                  failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_hmac_reset( mbedtls_md_context_t *ctx );
 
 /**
@@ -436,11 +448,13 @@
  * \return         #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
  *                 failure.
  */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_hmac( const mbedtls_md_info_t *md_info, const unsigned char *key, size_t keylen,
                 const unsigned char *input, size_t ilen,
                 unsigned char *output );
 
 /* Internal use */
+MBEDTLS_CHECK_RETURN_TYPICAL
 int mbedtls_md_process( mbedtls_md_context_t *ctx, const unsigned char *data );
 
 #ifdef __cplusplus
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 2d06fdd..e41455c 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -665,16 +665,25 @@
         }
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
         unsigned char mac[MBEDTLS_SSL_MAC_ADD];
+        int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
         ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
                                           transform->minor_ver,
                                           transform->taglen );
 
-        mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
-                                add_data_len );
-        mbedtls_md_hmac_update( &transform->md_ctx_enc, data, rec->data_len );
-        mbedtls_md_hmac_finish( &transform->md_ctx_enc, mac );
-        mbedtls_md_hmac_reset( &transform->md_ctx_enc );
+        ret = mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
+                                      add_data_len );
+        if( ret != 0 )
+            goto hmac_failed_etm_disabled;
+        ret = mbedtls_md_hmac_update( &transform->md_ctx_enc, data, rec->data_len );
+        if( ret != 0 )
+            goto hmac_failed_etm_disabled;
+        ret = mbedtls_md_hmac_finish( &transform->md_ctx_enc, mac );
+        if( ret != 0 )
+            goto hmac_failed_etm_disabled;
+        ret = mbedtls_md_hmac_reset( &transform->md_ctx_enc );
+        if( ret != 0 )
+            goto hmac_failed_etm_disabled;
 
         memcpy( data + rec->data_len, mac, transform->maclen );
 #endif
@@ -685,7 +694,14 @@
         rec->data_len += transform->maclen;
         post_avail -= transform->maclen;
         auth_done++;
+
+    hmac_failed_etm_disabled:
         mbedtls_platform_zeroize( mac, transform->maclen );
+        if( ret != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_hmac_xxx", ret );
+            return( ret );
+        }
     }
 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
 
@@ -928,19 +944,34 @@
             MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", add_data,
                                    add_data_len );
 
-            mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
-                                    add_data_len );
-            mbedtls_md_hmac_update( &transform->md_ctx_enc,
-                                    data, rec->data_len );
-            mbedtls_md_hmac_finish( &transform->md_ctx_enc, mac );
-            mbedtls_md_hmac_reset( &transform->md_ctx_enc );
+            ret = mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
+                                          add_data_len );
+            if( ret != 0 )
+                goto hmac_failed_etm_enabled;
+            ret = mbedtls_md_hmac_update( &transform->md_ctx_enc,
+                                          data, rec->data_len );
+            if( ret != 0 )
+                goto hmac_failed_etm_enabled;
+            ret = mbedtls_md_hmac_finish( &transform->md_ctx_enc, mac );
+            if( ret != 0 )
+                goto hmac_failed_etm_enabled;
+            ret = mbedtls_md_hmac_reset( &transform->md_ctx_enc );
+            if( ret != 0 )
+                goto hmac_failed_etm_enabled;
 
             memcpy( data + rec->data_len, mac, transform->maclen );
 
             rec->data_len += transform->maclen;
             post_avail -= transform->maclen;
             auth_done++;
+
+        hmac_failed_etm_enabled:
             mbedtls_platform_zeroize( mac, transform->maclen );
+            if( ret != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_RET( 1, "HMAC calculation failed", ret );
+                return( ret );
+            }
         }
 #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
     }
@@ -1211,12 +1242,20 @@
             /* Calculate expected MAC. */
             MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", add_data,
                                    add_data_len );
-            mbedtls_md_hmac_update( &transform->md_ctx_dec, add_data,
-                                    add_data_len );
-            mbedtls_md_hmac_update( &transform->md_ctx_dec,
+            ret = mbedtls_md_hmac_update( &transform->md_ctx_dec, add_data,
+                                          add_data_len );
+            if( ret != 0 )
+                goto hmac_failed_etm_enabled;
+            ret = mbedtls_md_hmac_update( &transform->md_ctx_dec,
                                     data, rec->data_len );
-            mbedtls_md_hmac_finish( &transform->md_ctx_dec, mac_expect );
-            mbedtls_md_hmac_reset( &transform->md_ctx_dec );
+            if( ret != 0 )
+                goto hmac_failed_etm_enabled;
+            ret = mbedtls_md_hmac_finish( &transform->md_ctx_dec, mac_expect );
+            if( ret != 0 )
+                goto hmac_failed_etm_enabled;
+            ret = mbedtls_md_hmac_reset( &transform->md_ctx_dec );
+            if( ret != 0 )
+                goto hmac_failed_etm_enabled;
 
             MBEDTLS_SSL_DEBUG_BUF( 4, "message  mac", data + rec->data_len,
                                    transform->maclen );
@@ -1224,7 +1263,6 @@
                                    transform->maclen );
 
             /* Compare expected MAC with MAC at the end of the record. */
-            ret = 0;
             if( mbedtls_ct_memcmp( data + rec->data_len, mac_expect,
                                               transform->maclen ) != 0 )
             {
@@ -1237,7 +1275,11 @@
         hmac_failed_etm_enabled:
             mbedtls_platform_zeroize( mac_expect, transform->maclen );
             if( ret != 0 )
+            {
+                if( ret != MBEDTLS_ERR_SSL_INVALID_MAC )
+                    MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_hmac_xxx", ret );
                 return( ret );
+            }
         }
 #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
 
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 046caec..a566f81 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -500,19 +500,37 @@
     if ( ( ret = mbedtls_md_setup( &md_ctx, md_info, 1 ) ) != 0 )
         goto exit;
 
-    mbedtls_md_hmac_starts( &md_ctx, secret, slen );
-    mbedtls_md_hmac_update( &md_ctx, tmp + md_len, nb );
-    mbedtls_md_hmac_finish( &md_ctx, tmp );
+    ret = mbedtls_md_hmac_starts( &md_ctx, secret, slen );
+    if( ret != 0 )
+        goto exit;
+    ret = mbedtls_md_hmac_update( &md_ctx, tmp + md_len, nb );
+    if( ret != 0 )
+        goto exit;
+    ret = mbedtls_md_hmac_finish( &md_ctx, tmp );
+    if( ret != 0 )
+        goto exit;
 
     for( i = 0; i < dlen; i += md_len )
     {
-        mbedtls_md_hmac_reset ( &md_ctx );
-        mbedtls_md_hmac_update( &md_ctx, tmp, md_len + nb );
-        mbedtls_md_hmac_finish( &md_ctx, h_i );
+        ret = mbedtls_md_hmac_reset ( &md_ctx );
+        if( ret != 0 )
+            goto exit;
+        ret = mbedtls_md_hmac_update( &md_ctx, tmp, md_len + nb );
+        if( ret != 0 )
+            goto exit;
+        ret = mbedtls_md_hmac_finish( &md_ctx, h_i );
+        if( ret != 0 )
+            goto exit;
 
-        mbedtls_md_hmac_reset ( &md_ctx );
-        mbedtls_md_hmac_update( &md_ctx, tmp, md_len );
-        mbedtls_md_hmac_finish( &md_ctx, tmp );
+        ret = mbedtls_md_hmac_reset ( &md_ctx );
+        if( ret != 0 )
+            goto exit;
+        ret = mbedtls_md_hmac_update( &md_ctx, tmp, md_len );
+        if( ret != 0 )
+            goto exit;
+        ret = mbedtls_md_hmac_finish( &md_ctx, tmp );
+        if( ret != 0 )
+            goto exit;
 
         k = ( i + md_len > dlen ) ? dlen % md_len : md_len;
 
@@ -958,8 +976,12 @@
        For AEAD-based ciphersuites, there is nothing to do here. */
     if( mac_key_len != 0 )
     {
-        mbedtls_md_hmac_starts( &transform->md_ctx_enc, mac_enc, mac_key_len );
-        mbedtls_md_hmac_starts( &transform->md_ctx_dec, mac_dec, mac_key_len );
+        ret = mbedtls_md_hmac_starts( &transform->md_ctx_enc, mac_enc, mac_key_len );
+        if( ret != 0 )
+            goto end;
+        ret = mbedtls_md_hmac_starts( &transform->md_ctx_dec, mac_dec, mac_key_len );
+        if( ret != 0 )
+            goto end;
     }
 #endif
 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */