diff --git a/library/asn1write.c b/library/asn1write.c
index 5922695..3811ef2 100644
--- a/library/asn1write.c
+++ b/library/asn1write.c
@@ -60,8 +60,8 @@
         if( *p - start < 3 )
             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-        *--(*p) = MBEDTLS_CHAR_0( len );
-        *--(*p) = MBEDTLS_CHAR_1( len );
+        *--(*p) = MBEDTLS_BYTE_0( len );
+        *--(*p) = MBEDTLS_BYTE_1( len );
         *--(*p) = 0x82;
         return( 3 );
     }
@@ -71,9 +71,9 @@
         if( *p - start < 4 )
             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-        *--(*p) = MBEDTLS_CHAR_0( len );
-        *--(*p) = MBEDTLS_CHAR_1( len );
-        *--(*p) = MBEDTLS_CHAR_2( len );
+        *--(*p) = MBEDTLS_BYTE_0( len );
+        *--(*p) = MBEDTLS_BYTE_1( len );
+        *--(*p) = MBEDTLS_BYTE_2( len );
         *--(*p) = 0x83;
         return( 4 );
     }
@@ -85,10 +85,10 @@
         if( *p - start < 5 )
             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-        *--(*p) = MBEDTLS_CHAR_0( len );
-        *--(*p) = MBEDTLS_CHAR_1( len );
-        *--(*p) = MBEDTLS_CHAR_2( len );
-        *--(*p) = MBEDTLS_CHAR_3( len );
+        *--(*p) = MBEDTLS_BYTE_0( len );
+        *--(*p) = MBEDTLS_BYTE_1( len );
+        *--(*p) = MBEDTLS_BYTE_2( len );
+        *--(*p) = MBEDTLS_BYTE_3( len );
         *--(*p) = 0x84;
         return( 5 );
     }
diff --git a/library/ccm.c b/library/ccm.c
index 95d90dc..0188075 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -200,7 +200,7 @@
     memcpy( b + 1, iv, iv_len );
 
     for( i = 0, len_left = length; i < q; i++, len_left >>= 8 )
-        b[15-i] = MBEDTLS_CHAR_0( len_left );
+        b[15-i] = MBEDTLS_BYTE_0( len_left );
 
     if( len_left > 0 )
         return( MBEDTLS_ERR_CCM_BAD_INPUT );
@@ -221,8 +221,8 @@
         src = add;
 
         memset( b, 0, 16 );
-        b[0] = MBEDTLS_CHAR_1( add_len );
-        b[1] = MBEDTLS_CHAR_0( add_len );
+        b[0] = MBEDTLS_BYTE_1( add_len );
+        b[1] = MBEDTLS_BYTE_0( add_len );
 
         use_len = len_left < 16 - 2 ? len_left : 16 - 2;
         memcpy( b + 2, src, use_len );
diff --git a/library/common.h b/library/common.h
index 95a30c9..ea01692 100644
--- a/library/common.h
+++ b/library/common.h
@@ -29,6 +29,8 @@
 #include "mbedtls/config.h"
 #endif
 
+#include <stdint.h>
+
 /** Helper to define a function as static except when building invasive tests.
  *
  * If a function is only used inside its own source file and should be
@@ -63,19 +65,14 @@
  * Using MBEDTLS_BYTE_a will shift a*8 bits
  * to retrieve the next byte of information
  */
-#define MBEDTLS_BYTE_0( x ) ( (uint8_t) ( ( x ) & 0xff ) )
+#define MBEDTLS_BYTE_0( x ) ( (uint8_t) (   ( x )         & 0xff ) )
 #define MBEDTLS_BYTE_1( x ) ( (uint8_t) ( ( ( x ) >> 8  ) & 0xff ) )
 #define MBEDTLS_BYTE_2( x ) ( (uint8_t) ( ( ( x ) >> 16 ) & 0xff ) )
 #define MBEDTLS_BYTE_3( x ) ( (uint8_t) ( ( ( x ) >> 24 ) & 0xff ) )
-
-#define MBEDTLS_CHAR_0( x ) ( (unsigned char) (   ( x )         & 0xff ) )
-#define MBEDTLS_CHAR_1( x ) ( (unsigned char) ( ( ( x ) >> 8  ) & 0xff ) )
-#define MBEDTLS_CHAR_2( x ) ( (unsigned char) ( ( ( x ) >> 16 ) & 0xff ) )
-#define MBEDTLS_CHAR_3( x ) ( (unsigned char) ( ( ( x ) >> 24 ) & 0xff ) )
-#define MBEDTLS_CHAR_4( x ) ( (unsigned char) ( ( ( x ) >> 32 ) & 0xff ) )
-#define MBEDTLS_CHAR_5( x ) ( (unsigned char) ( ( ( x ) >> 40 ) & 0xff ) )
-#define MBEDTLS_CHAR_6( x ) ( (unsigned char) ( ( ( x ) >> 48 ) & 0xff ) )
-#define MBEDTLS_CHAR_7( x ) ( (unsigned char) ( ( ( x ) >> 56 ) & 0xff ) )
+#define MBEDTLS_BYTE_4( x ) ( (uint8_t) ( ( ( x ) >> 32 ) & 0xff ) )
+#define MBEDTLS_BYTE_5( x ) ( (uint8_t) ( ( ( x ) >> 40 ) & 0xff ) )
+#define MBEDTLS_BYTE_6( x ) ( (uint8_t) ( ( ( x ) >> 48 ) & 0xff ) )
+#define MBEDTLS_BYTE_7( x ) ( (uint8_t) ( ( ( x ) >> 56 ) & 0xff ) )
 
 /**
  * Get the unsigned 32 bits integer corresponding to four bytes in
diff --git a/library/ecjpake.c b/library/ecjpake.c
index 98c025b..a058337 100644
--- a/library/ecjpake.c
+++ b/library/ecjpake.c
@@ -166,10 +166,10 @@
     if( ret != 0 )
         return( ret );
 
-    (*p)[0] = MBEDTLS_CHAR_3( len );
-    (*p)[1] = MBEDTLS_CHAR_2( len );
-    (*p)[2] = MBEDTLS_CHAR_1( len );
-    (*p)[3] = MBEDTLS_CHAR_0( len );
+    (*p)[0] = MBEDTLS_BYTE_3( len );
+    (*p)[1] = MBEDTLS_BYTE_2( len );
+    (*p)[2] = MBEDTLS_BYTE_1( len );
+    (*p)[3] = MBEDTLS_BYTE_0( len );
 
     *p += 4 + len;
 
@@ -209,10 +209,10 @@
     if( end - p < 4 )
         return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
 
-    *p++ = MBEDTLS_CHAR_3( id_len );
-    *p++ = MBEDTLS_CHAR_2( id_len );
-    *p++ = MBEDTLS_CHAR_1( id_len );
-    *p++ = MBEDTLS_CHAR_0( id_len );
+    *p++ = MBEDTLS_BYTE_3( id_len );
+    *p++ = MBEDTLS_BYTE_2( id_len );
+    *p++ = MBEDTLS_BYTE_1( id_len );
+    *p++ = MBEDTLS_BYTE_0( id_len );
 
     if( end < p || (size_t)( end - p ) < id_len )
         return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
@@ -352,7 +352,7 @@
         goto cleanup;
     }
 
-    *(*p)++ = MBEDTLS_CHAR_0( len );
+    *(*p)++ = MBEDTLS_BYTE_0( len );
     MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &h, *p, len ) ); /* r */
     *p += len;
 
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index aefcf22..9793e3c 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -136,18 +136,18 @@
      * } ServerNameList;
      *
      */
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SERVERNAME );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SERVERNAME );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_SERVERNAME );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_SERVERNAME );
 
-    *p++ = MBEDTLS_CHAR_1( hostname_len + 5);
-    *p++ = MBEDTLS_CHAR_0( hostname_len + 5);
+    *p++ = MBEDTLS_BYTE_1( hostname_len + 5);
+    *p++ = MBEDTLS_BYTE_0( hostname_len + 5);
 
-    *p++ = MBEDTLS_CHAR_1( hostname_len + 3 );
-    *p++ = MBEDTLS_CHAR_0( hostname_len + 3 );
+    *p++ = MBEDTLS_BYTE_1( hostname_len + 3 );
+    *p++ = MBEDTLS_BYTE_0( hostname_len + 3 );
 
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME );
-    *p++ = MBEDTLS_CHAR_1( hostname_len );
-    *p++ = MBEDTLS_CHAR_0( hostname_len );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME );
+    *p++ = MBEDTLS_BYTE_1( hostname_len );
+    *p++ = MBEDTLS_BYTE_0( hostname_len );
 
     memcpy( p, ssl->hostname, hostname_len );
 
@@ -181,12 +181,12 @@
     /*
      * Secure renegotiation
      */
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
 
     *p++ = 0x00;
-    *p++ = MBEDTLS_CHAR_0( ssl->verify_data_len + 1 );
-    *p++ = MBEDTLS_CHAR_0( ssl->verify_data_len );
+    *p++ = MBEDTLS_BYTE_0( ssl->verify_data_len + 1 );
+    *p++ = MBEDTLS_BYTE_0( ssl->verify_data_len );
 
     memcpy( p, ssl->own_verify_data, ssl->verify_data_len );
 
@@ -281,14 +281,14 @@
      * SignatureAndHashAlgorithm
      *   supported_signature_algorithms<2..2^16-2>;
      */
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SIG_ALG );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SIG_ALG );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_SIG_ALG );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_SIG_ALG );
 
-    *p++ = MBEDTLS_CHAR_1( sig_alg_len + 2 );
-    *p++ = MBEDTLS_CHAR_0( sig_alg_len + 2 );
+    *p++ = MBEDTLS_BYTE_1( sig_alg_len + 2 );
+    *p++ = MBEDTLS_BYTE_0( sig_alg_len + 2 );
 
-    *p++ = MBEDTLS_CHAR_1( sig_alg_len );
-    *p++ = MBEDTLS_CHAR_0( sig_alg_len );
+    *p++ = MBEDTLS_BYTE_1( sig_alg_len );
+    *p++ = MBEDTLS_BYTE_0( sig_alg_len );
 
     *olen = 6 + sig_alg_len;
 
@@ -356,14 +356,14 @@
         elliptic_curve_list[elliptic_curve_len++] = info->tls_id & 0xFF;
     }
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES );
 
-    *p++ = MBEDTLS_CHAR_1( elliptic_curve_len + 2 );
-    *p++ = MBEDTLS_CHAR_0( elliptic_curve_len + 2 );
+    *p++ = MBEDTLS_BYTE_1( elliptic_curve_len + 2 );
+    *p++ = MBEDTLS_BYTE_0( elliptic_curve_len + 2 );
 
-    *p++ = MBEDTLS_CHAR_1( elliptic_curve_len     );
-    *p++ = MBEDTLS_CHAR_0( elliptic_curve_len     );
+    *p++ = MBEDTLS_BYTE_1( elliptic_curve_len     );
+    *p++ = MBEDTLS_BYTE_0( elliptic_curve_len     );
 
     *olen = 6 + elliptic_curve_len;
 
@@ -384,8 +384,8 @@
         ( "client hello, adding supported_point_formats extension" ) );
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
 
     *p++ = 0x00;
     *p++ = 2;
@@ -421,8 +421,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
 
     /*
      * We may need to send ClientHello multiple times for Hello verification.
@@ -464,8 +464,8 @@
         memcpy( p + 2, ssl->handshake->ecjpake_cache, kkpp_len );
     }
 
-    *p++ = MBEDTLS_CHAR_1( kkpp_len );
-    *p++ = MBEDTLS_CHAR_0( kkpp_len );
+    *p++ = MBEDTLS_BYTE_1( kkpp_len );
+    *p++ = MBEDTLS_BYTE_0( kkpp_len );
 
     *olen = kkpp_len + 4;
 
@@ -504,11 +504,11 @@
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, (unsigned)( ssl->own_cid_len + 5 ) );
 
     /* Add extension ID + size */
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_CID );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_CID );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_CID );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_CID );
     ext_len = (size_t) ssl->own_cid_len + 1;
-    *p++ = MBEDTLS_CHAR_1( ext_len );
-    *p++ = MBEDTLS_CHAR_0( ext_len );
+    *p++ = MBEDTLS_BYTE_1( ext_len );
+    *p++ = MBEDTLS_BYTE_0( ext_len );
 
     *p++ = (uint8_t) ssl->own_cid_len;
     memcpy( p, ssl->own_cid, ssl->own_cid_len );
@@ -537,8 +537,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 5 );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
 
     *p++ = 0x00;
     *p++ = 1;
@@ -600,8 +600,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -631,8 +631,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -663,11 +663,11 @@
     /* The addition is safe here since the ticket length is 16 bit. */
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 + tlen );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SESSION_TICKET );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SESSION_TICKET );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_SESSION_TICKET );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_SESSION_TICKET );
 
-    *p++ = MBEDTLS_CHAR_1( tlen );
-    *p++ = MBEDTLS_CHAR_0( tlen );
+    *p++ = MBEDTLS_BYTE_1( tlen );
+    *p++ = MBEDTLS_BYTE_0( tlen );
 
     *olen = 4;
 
@@ -707,8 +707,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 + alpnlen );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ALPN );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ALPN );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_ALPN );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_ALPN );
 
     /*
      * opaque ProtocolName<1..2^8-1>;
@@ -735,12 +735,12 @@
     *olen = p - buf;
 
     /* List length = olen - 2 (ext_type) - 2 (ext_len) - 2 (list_len) */
-    buf[4] = MBEDTLS_CHAR_1( *olen - 6 );
-    buf[5] = MBEDTLS_CHAR_0( *olen - 6 );
+    buf[4] = MBEDTLS_BYTE_1( *olen - 6 );
+    buf[5] = MBEDTLS_BYTE_0( *olen - 6 );
 
     /* Extension length = olen - 2 (ext_type) - 2 (ext_len) */
-    buf[2] = MBEDTLS_CHAR_1( *olen - 4 );
-    buf[3] = MBEDTLS_CHAR_0( *olen - 4 );
+    buf[2] = MBEDTLS_BYTE_1( *olen - 4 );
+    buf[3] = MBEDTLS_BYTE_0( *olen - 4 );
 
     return( 0 );
 }
@@ -792,12 +792,12 @@
      */
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, ext_len + 4 );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_USE_SRTP );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_USE_SRTP );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_USE_SRTP );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_USE_SRTP );
 
 
-    *p++ = MBEDTLS_CHAR_1( ext_len & 0xFF00 );
-    *p++ = MBEDTLS_CHAR_0( ext_len );
+    *p++ = MBEDTLS_BYTE_1( ext_len & 0xFF00 );
+    *p++ = MBEDTLS_BYTE_0( ext_len );
 
     /* protection profile length: 2*(ssl->conf->dtls_srtp_profile_list_len) */
     /* micro-optimization:
@@ -808,7 +808,7 @@
      *                        >> 8 ) & 0xFF );
      */
     *p++ = 0;
-    *p++ = MBEDTLS_CHAR_0( 2 * ssl->conf->dtls_srtp_profile_list_len );
+    *p++ = MBEDTLS_BYTE_0( 2 * ssl->conf->dtls_srtp_profile_list_len );
 
     for( protection_profiles_index=0;
          protection_profiles_index < ssl->conf->dtls_srtp_profile_list_len;
@@ -1417,8 +1417,8 @@
     {
         /* No need to check for space here, because the extension
          * writing functions already took care of that. */
-        *p++ = MBEDTLS_CHAR_1( ext_len );
-        *p++ = MBEDTLS_CHAR_0( ext_len );
+        *p++ = MBEDTLS_BYTE_1( ext_len );
+        *p++ = MBEDTLS_BYTE_0( ext_len );
         p += ext_len;
     }
 
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index b001a02..fdafa8b 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -454,15 +454,15 @@
         *cur = rec->cid_len;
         cur++;
 
-        cur[0] = MBEDTLS_CHAR_1( rec->data_len );
-        cur[1] = MBEDTLS_CHAR_0( rec->data_len );
+        cur[0] = MBEDTLS_BYTE_1( rec->data_len );
+        cur[1] = MBEDTLS_BYTE_0( rec->data_len );
         cur += 2;
     }
     else
 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
     {
-        cur[0] = MBEDTLS_CHAR_1( rec->data_len );
-        cur[1] = MBEDTLS_CHAR_0( rec->data_len );
+        cur[0] = MBEDTLS_BYTE_1( rec->data_len );
+        cur[1] = MBEDTLS_BYTE_0( rec->data_len );
         cur += 2;
     }
 
@@ -2759,8 +2759,8 @@
             /* Write message_seq and update it, except for HelloRequest */
             if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
             {
-                ssl->out_msg[4] = MBEDTLS_CHAR_1( ssl->handshake->out_msg_seq );
-                ssl->out_msg[5] = MBEDTLS_CHAR_0( ssl->handshake->out_msg_seq );
+                ssl->out_msg[4] = MBEDTLS_BYTE_1( ssl->handshake->out_msg_seq );
+                ssl->out_msg[5] = MBEDTLS_BYTE_0( ssl->handshake->out_msg_seq );
                 ++( ssl->handshake->out_msg_seq );
             }
             else
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 319902e..e195137 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2335,11 +2335,11 @@
      *   } ConnectionId;
     */
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_CID );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_CID );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_CID );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_CID );
     ext_len = (size_t) ssl->own_cid_len + 1;
-    *p++ = MBEDTLS_CHAR_1( ext_len );
-    *p++ = MBEDTLS_CHAR_0( ext_len );
+    *p++ = MBEDTLS_BYTE_1( ext_len );
+    *p++ = MBEDTLS_BYTE_0( ext_len );
 
     *p++ = (uint8_t) ssl->own_cid_len;
     memcpy( p, ssl->own_cid, ssl->own_cid_len );
@@ -2381,8 +2381,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding encrypt then mac extension" ) );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2408,8 +2408,8 @@
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding extended master secret "
                         "extension" ) );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2433,8 +2433,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding session ticket extension" ) );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SESSION_TICKET );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SESSION_TICKET );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_SESSION_TICKET );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_SESSION_TICKET );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2457,8 +2457,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, secure renegotiation extension" ) );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
 
 #if defined(MBEDTLS_SSL_RENEGOTIATION)
     if( ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE )
@@ -2498,8 +2498,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, max_fragment_length extension" ) );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
 
     *p++ = 0x00;
     *p++ = 1;
@@ -2528,8 +2528,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, supported_point_formats extension" ) );
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
 
     *p++ = 0x00;
     *p++ = 2;
@@ -2566,8 +2566,8 @@
         return;
     }
 
-    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
-    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
+    *p++ = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
 
     ret = mbedtls_ecjpake_write_round_one( &ssl->handshake->ecjpake_ctx,
                                         p + 2, end - p - 2, &kkpp_len,
@@ -2578,8 +2578,8 @@
         return;
     }
 
-    *p++ = MBEDTLS_CHAR_1( kkpp_len );
-    *p++ = MBEDTLS_CHAR_0( kkpp_len );
+    *p++ = MBEDTLS_BYTE_1( kkpp_len );
+    *p++ = MBEDTLS_BYTE_0( kkpp_len );
 
     *olen = kkpp_len + 4;
 }
@@ -2604,18 +2604,18 @@
      * 6 . 6    protocol name length
      * 7 . 7+n  protocol name
      */
-    buf[0] = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ALPN );
-    buf[1] = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ALPN );
+    buf[0] = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_ALPN );
+    buf[1] = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_ALPN );
 
     *olen = 7 + strlen( ssl->alpn_chosen );
 
-    buf[2] = MBEDTLS_CHAR_1( *olen - 4 );
-    buf[3] = MBEDTLS_CHAR_0( *olen - 4 );
+    buf[2] = MBEDTLS_BYTE_1( *olen - 4 );
+    buf[3] = MBEDTLS_BYTE_0( *olen - 4 );
 
-    buf[4] = MBEDTLS_CHAR_1( *olen - 6 );
-    buf[5] = MBEDTLS_CHAR_0( *olen - 6 );
+    buf[4] = MBEDTLS_BYTE_1( *olen - 6 );
+    buf[5] = MBEDTLS_BYTE_0( *olen - 6 );
 
-    buf[6] = MBEDTLS_CHAR_0( *olen - 7 );
+    buf[6] = MBEDTLS_BYTE_0( *olen - 7 );
 
     memcpy( buf + 7, ssl->alpn_chosen, *olen - 7 );
 }
@@ -2660,15 +2660,15 @@
     }
 
     /* extension */
-    buf[0] = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_USE_SRTP );
-    buf[1] = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_USE_SRTP );
+    buf[0] = MBEDTLS_BYTE_1( MBEDTLS_TLS_EXT_USE_SRTP );
+    buf[1] = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_USE_SRTP );
     /*
      * total length 5 and mki value: only one profile(2 bytes)
      *              and length(2 bytes) and srtp_mki  )
      */
     ext_len = 5 + mki_len;
-    buf[2] = MBEDTLS_CHAR_1( ext_len );
-    buf[3] = MBEDTLS_CHAR_0( ext_len );
+    buf[2] = MBEDTLS_BYTE_1( ext_len );
+    buf[3] = MBEDTLS_BYTE_0( ext_len );
 
     /* protection profile length: 2 */
     buf[4] = 0x00;
@@ -2677,8 +2677,8 @@
                                 ssl->dtls_srtp_info.chosen_dtls_srtp_profile );
     if( profile_value != MBEDTLS_TLS_SRTP_UNSET )
     {
-        buf[6] = MBEDTLS_CHAR_1( profile_value );
-        buf[7] = MBEDTLS_CHAR_0( profile_value );
+        buf[6] = MBEDTLS_BYTE_1( profile_value );
+        buf[7] = MBEDTLS_BYTE_0( profile_value );
     }
     else
     {
@@ -3026,8 +3026,8 @@
 
     if( ext_len > 0 )
     {
-        *p++ = MBEDTLS_CHAR_1( ext_len );
-        *p++ = MBEDTLS_CHAR_0( ext_len );
+        *p++ = MBEDTLS_BYTE_1( ext_len );
+        *p++ = MBEDTLS_BYTE_0( ext_len );
         p += ext_len;
     }
 
@@ -4646,13 +4646,13 @@
         tlen = 0;
     }
 
-    ssl->out_msg[4] = MBEDTLS_CHAR_3( lifetime );
-    ssl->out_msg[5] = MBEDTLS_CHAR_2( lifetime );
-    ssl->out_msg[6] = MBEDTLS_CHAR_1( lifetime );
-    ssl->out_msg[7] = MBEDTLS_CHAR_0( lifetime );
+    ssl->out_msg[4] = MBEDTLS_BYTE_3( lifetime );
+    ssl->out_msg[5] = MBEDTLS_BYTE_2( lifetime );
+    ssl->out_msg[6] = MBEDTLS_BYTE_1( lifetime );
+    ssl->out_msg[7] = MBEDTLS_BYTE_0( lifetime );
 
-    ssl->out_msg[8] = MBEDTLS_CHAR_1( tlen );
-    ssl->out_msg[9] = MBEDTLS_CHAR_0( tlen );
+    ssl->out_msg[8] = MBEDTLS_BYTE_1( tlen );
+    ssl->out_msg[9] = MBEDTLS_BYTE_0( tlen );
 
     ssl->out_msglen = 10 + tlen;
 
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 2c3e506..25d4a3e 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -5278,8 +5278,8 @@
     MBEDTLS_VERSION_MAJOR,
     MBEDTLS_VERSION_MINOR,
     MBEDTLS_VERSION_PATCH,
-    MBEDTLS_CHAR_1( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
-    MBEDTLS_CHAR_0( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_1( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_0( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
 };
 
 /*
@@ -5360,14 +5360,14 @@
     {
         start = (uint64_t) session->start;
 
-        *p++ = MBEDTLS_CHAR_7( start );
-        *p++ = MBEDTLS_CHAR_6( start );
-        *p++ = MBEDTLS_CHAR_5( start );
-        *p++ = MBEDTLS_CHAR_4( start );
-        *p++ = MBEDTLS_CHAR_3( start );
-        *p++ = MBEDTLS_CHAR_2( start );
-        *p++ = MBEDTLS_CHAR_1( start );
-        *p++ = MBEDTLS_CHAR_0( start );
+        *p++ = MBEDTLS_BYTE_7( start );
+        *p++ = MBEDTLS_BYTE_6( start );
+        *p++ = MBEDTLS_BYTE_5( start );
+        *p++ = MBEDTLS_BYTE_4( start );
+        *p++ = MBEDTLS_BYTE_3( start );
+        *p++ = MBEDTLS_BYTE_2( start );
+        *p++ = MBEDTLS_BYTE_1( start );
+        *p++ = MBEDTLS_BYTE_0( start );
     }
 #endif /* MBEDTLS_HAVE_TIME */
 
@@ -5383,22 +5383,22 @@
 
     if( used <= buf_len )
     {
-        *p++ = MBEDTLS_CHAR_1( session->ciphersuite );
-        *p++ = MBEDTLS_CHAR_0( session->ciphersuite );
+        *p++ = MBEDTLS_BYTE_1( session->ciphersuite );
+        *p++ = MBEDTLS_BYTE_0( session->ciphersuite );
 
-        *p++ = MBEDTLS_CHAR_0( session->compression );
+        *p++ = MBEDTLS_BYTE_0( session->compression );
 
-        *p++ = MBEDTLS_CHAR_0( session->id_len );
+        *p++ = MBEDTLS_BYTE_0( session->id_len );
         memcpy( p, session->id, 32 );
         p += 32;
 
         memcpy( p, session->master, 48 );
         p += 48;
 
-        *p++ = MBEDTLS_CHAR_3( session->verify_result );
-        *p++ = MBEDTLS_CHAR_2( session->verify_result );
-        *p++ = MBEDTLS_CHAR_1( session->verify_result );
-        *p++ = MBEDTLS_CHAR_0( session->verify_result );
+        *p++ = MBEDTLS_BYTE_3( session->verify_result );
+        *p++ = MBEDTLS_BYTE_2( session->verify_result );
+        *p++ = MBEDTLS_BYTE_1( session->verify_result );
+        *p++ = MBEDTLS_BYTE_0( session->verify_result );
     }
 
     /*
@@ -5415,9 +5415,9 @@
 
     if( used <= buf_len )
     {
-        *p++ = MBEDTLS_CHAR_2( cert_len );
-        *p++ = MBEDTLS_CHAR_1( cert_len );
-        *p++ = MBEDTLS_CHAR_0( cert_len );
+        *p++ = MBEDTLS_BYTE_2( cert_len );
+        *p++ = MBEDTLS_BYTE_1( cert_len );
+        *p++ = MBEDTLS_BYTE_0( cert_len );
 
         if( session->peer_cert != NULL )
         {
@@ -5458,9 +5458,9 @@
 
     if( used <= buf_len )
     {
-        *p++ = MBEDTLS_CHAR_2( session->ticket_len );
-        *p++ = MBEDTLS_CHAR_1( session->ticket_len );
-        *p++ = MBEDTLS_CHAR_0( session->ticket_len );
+        *p++ = MBEDTLS_BYTE_2( session->ticket_len );
+        *p++ = MBEDTLS_BYTE_1( session->ticket_len );
+        *p++ = MBEDTLS_BYTE_0( session->ticket_len );
 
         if( session->ticket != NULL )
         {
@@ -5468,10 +5468,10 @@
             p += session->ticket_len;
         }
 
-        *p++ = MBEDTLS_CHAR_3( session->ticket_lifetime );
-        *p++ = MBEDTLS_CHAR_2( session->ticket_lifetime );
-        *p++ = MBEDTLS_CHAR_1( session->ticket_lifetime );
-        *p++ = MBEDTLS_CHAR_0( session->ticket_lifetime );
+        *p++ = MBEDTLS_BYTE_3( session->ticket_lifetime );
+        *p++ = MBEDTLS_BYTE_2( session->ticket_lifetime );
+        *p++ = MBEDTLS_BYTE_1( session->ticket_lifetime );
+        *p++ = MBEDTLS_BYTE_0( session->ticket_lifetime );
     }
 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
 
@@ -5496,7 +5496,7 @@
     used += 1;
 
     if( used <= buf_len )
-        *p++ = MBEDTLS_CHAR_0( session->encrypt_then_mac );
+        *p++ = MBEDTLS_BYTE_0( session->encrypt_then_mac );
 #endif
 
     /* Done */
@@ -6149,11 +6149,11 @@
     MBEDTLS_VERSION_MAJOR,
     MBEDTLS_VERSION_MINOR,
     MBEDTLS_VERSION_PATCH,
-    MBEDTLS_CHAR_1( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
-    MBEDTLS_CHAR_0( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
-    MBEDTLS_CHAR_2( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
-    MBEDTLS_CHAR_1( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
-    MBEDTLS_CHAR_0( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_1( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_0( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_2( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_1( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_0( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
 };
 
 /*
@@ -6294,10 +6294,10 @@
     used += 4 + session_len;
     if( used <= buf_len )
     {
-        *p++ = MBEDTLS_CHAR_3( session_len );
-        *p++ = MBEDTLS_CHAR_2( session_len );
-        *p++ = MBEDTLS_CHAR_1( session_len );
-        *p++ = MBEDTLS_CHAR_0( session_len );
+        *p++ = MBEDTLS_BYTE_3( session_len );
+        *p++ = MBEDTLS_BYTE_2( session_len );
+        *p++ = MBEDTLS_BYTE_1( session_len );
+        *p++ = MBEDTLS_BYTE_0( session_len );
 
         ret = ssl_session_save( ssl->session, 1,
                                 p, session_len, &session_len );
@@ -6339,10 +6339,10 @@
     used += 4;
     if( used <= buf_len )
     {
-        *p++ = MBEDTLS_CHAR_3( ssl->badmac_seen );
-        *p++ = MBEDTLS_CHAR_2( ssl->badmac_seen );
-        *p++ = MBEDTLS_CHAR_1( ssl->badmac_seen );
-        *p++ = MBEDTLS_CHAR_0( ssl->badmac_seen );
+        *p++ = MBEDTLS_BYTE_3( ssl->badmac_seen );
+        *p++ = MBEDTLS_BYTE_2( ssl->badmac_seen );
+        *p++ = MBEDTLS_BYTE_1( ssl->badmac_seen );
+        *p++ = MBEDTLS_BYTE_0( ssl->badmac_seen );
     }
 #endif /* MBEDTLS_SSL_DTLS_BADMAC_LIMIT */
 
@@ -6350,23 +6350,23 @@
     used += 16;
     if( used <= buf_len )
     {
-        *p++ = MBEDTLS_CHAR_7( ssl->in_window_top );
-        *p++ = MBEDTLS_CHAR_6( ssl->in_window_top );
-        *p++ = MBEDTLS_CHAR_5( ssl->in_window_top );
-        *p++ = MBEDTLS_CHAR_4( ssl->in_window_top );
-        *p++ = MBEDTLS_CHAR_3( ssl->in_window_top );
-        *p++ = MBEDTLS_CHAR_2( ssl->in_window_top );
-        *p++ = MBEDTLS_CHAR_1( ssl->in_window_top );
-        *p++ = MBEDTLS_CHAR_0( ssl->in_window_top );
+        *p++ = MBEDTLS_BYTE_7( ssl->in_window_top );
+        *p++ = MBEDTLS_BYTE_6( ssl->in_window_top );
+        *p++ = MBEDTLS_BYTE_5( ssl->in_window_top );
+        *p++ = MBEDTLS_BYTE_4( ssl->in_window_top );
+        *p++ = MBEDTLS_BYTE_3( ssl->in_window_top );
+        *p++ = MBEDTLS_BYTE_2( ssl->in_window_top );
+        *p++ = MBEDTLS_BYTE_1( ssl->in_window_top );
+        *p++ = MBEDTLS_BYTE_0( ssl->in_window_top );
 
-        *p++ = MBEDTLS_CHAR_7( ssl->in_window );
-        *p++ = MBEDTLS_CHAR_6( ssl->in_window );
-        *p++ = MBEDTLS_CHAR_5( ssl->in_window );
-        *p++ = MBEDTLS_CHAR_4( ssl->in_window );
-        *p++ = MBEDTLS_CHAR_3( ssl->in_window );
-        *p++ = MBEDTLS_CHAR_2( ssl->in_window );
-        *p++ = MBEDTLS_CHAR_1( ssl->in_window );
-        *p++ = MBEDTLS_CHAR_0( ssl->in_window );
+        *p++ = MBEDTLS_BYTE_7( ssl->in_window );
+        *p++ = MBEDTLS_BYTE_6( ssl->in_window );
+        *p++ = MBEDTLS_BYTE_5( ssl->in_window );
+        *p++ = MBEDTLS_BYTE_4( ssl->in_window );
+        *p++ = MBEDTLS_BYTE_3( ssl->in_window );
+        *p++ = MBEDTLS_BYTE_2( ssl->in_window );
+        *p++ = MBEDTLS_BYTE_1( ssl->in_window );
+        *p++ = MBEDTLS_BYTE_0( ssl->in_window );
     }
 #endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
 
@@ -6389,8 +6389,8 @@
     used += 2;
     if( used <= buf_len )
     {
-        *p++ = MBEDTLS_CHAR_1( ssl->mtu );
-        *p++ = MBEDTLS_CHAR_0( ssl->mtu );
+        *p++ = MBEDTLS_BYTE_1( ssl->mtu );
+        *p++ = MBEDTLS_BYTE_0( ssl->mtu );
     }
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 4b84cb4..3de6f03 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -112,17 +112,17 @@
 #endif
 
     *p++ = 0;
-    *p++ = MBEDTLS_CHAR_0( desired_length );
+    *p++ = MBEDTLS_BYTE_0( desired_length );
 
     /* Add label incl. prefix */
-    *p++ = MBEDTLS_CHAR_0( total_label_len );
+    *p++ = MBEDTLS_BYTE_0( total_label_len );
     memcpy( p, tls1_3_label_prefix, sizeof(tls1_3_label_prefix) );
     p += sizeof(tls1_3_label_prefix);
     memcpy( p, label, llen );
     p += llen;
 
     /* Add context value */
-    *p++ = MBEDTLS_CHAR_0( clen );
+    *p++ = MBEDTLS_BYTE_0( clen );
     if( clen != 0 )
         memcpy( p, ctx, clen );