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;