diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 59c5460..7d65479 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -136,18 +136,18 @@
      * } ServerNameList;
      *
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SERVERNAME );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SERVERNAME );
 
-    *p++ = (unsigned char)( ( (hostname_len + 5) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( (hostname_len + 5)      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( hostname_len + 5);
+    *p++ = MBEDTLS_CHAR_0( hostname_len + 5);
 
-    *p++ = (unsigned char)( ( (hostname_len + 3) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( (hostname_len + 3)      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( hostname_len + 3 );
+    *p++ = MBEDTLS_CHAR_0( hostname_len + 3 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME ) & 0xFF );
-    *p++ = (unsigned char)( ( hostname_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( hostname_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME );
+    *p++ = MBEDTLS_CHAR_1( hostname_len );
+    *p++ = MBEDTLS_CHAR_0( hostname_len );
 
     memcpy( p, ssl->hostname, hostname_len );
 
@@ -181,14 +181,12 @@
     /*
      * Secure renegotiation
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
 
     *p++ = 0x00;
-    *p++ = ( ssl->verify_data_len + 1 ) & 0xFF;
-    *p++ = ssl->verify_data_len & 0xFF;
+    *p++ = MBEDTLS_CHAR_0( ssl->verify_data_len + 1 );
+    *p++ = MBEDTLS_CHAR_0( ssl->verify_data_len );
 
     memcpy( p, ssl->own_verify_data, ssl->verify_data_len );
 
@@ -283,14 +281,14 @@
      * SignatureAndHashAlgorithm
      *   supported_signature_algorithms<2..2^16-2>;
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SIG_ALG );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SIG_ALG );
 
-    *p++ = (unsigned char)( ( ( sig_alg_len + 2 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( sig_alg_len + 2 )      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( sig_alg_len + 2 );
+    *p++ = MBEDTLS_CHAR_0( sig_alg_len + 2 );
 
-    *p++ = (unsigned char)( ( sig_alg_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( sig_alg_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( sig_alg_len );
+    *p++ = MBEDTLS_CHAR_0( sig_alg_len );
 
     *olen = 6 + sig_alg_len;
 
@@ -358,16 +356,14 @@
         elliptic_curve_list[elliptic_curve_len++] = info->tls_id & 0xFF;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES );
 
-    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 )      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( elliptic_curve_len + 2 );
+    *p++ = MBEDTLS_CHAR_0( elliptic_curve_len + 2 );
 
-    *p++ = (unsigned char)( ( ( elliptic_curve_len     ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( elliptic_curve_len     )      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( elliptic_curve_len     );
+    *p++ = MBEDTLS_CHAR_0( elliptic_curve_len     );
 
     *olen = 6 + elliptic_curve_len;
 
@@ -388,10 +384,8 @@
         ( "client hello, adding supported_point_formats extension" ) );
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
 
     *p++ = 0x00;
     *p++ = 2;
@@ -427,8 +421,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
 
     /*
      * We may need to send ClientHello multiple times for Hello verification.
@@ -470,8 +464,8 @@
         memcpy( p + 2, ssl->handshake->ecjpake_cache, kkpp_len );
     }
 
-    *p++ = (unsigned char)( ( kkpp_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( kkpp_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( kkpp_len );
+    *p++ = MBEDTLS_CHAR_0( kkpp_len );
 
     *olen = kkpp_len + 4;
 
@@ -510,11 +504,11 @@
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, (unsigned)( ssl->own_cid_len + 5 ) );
 
     /* Add extension ID + size */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_CID );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_CID );
     ext_len = (size_t) ssl->own_cid_len + 1;
-    *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( ext_len );
+    *p++ = MBEDTLS_CHAR_0( ext_len );
 
     *p++ = (uint8_t) ssl->own_cid_len;
     memcpy( p, ssl->own_cid, ssl->own_cid_len );
@@ -543,10 +537,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 5 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
 
     *p++ = 0x00;
     *p++ = 1;
@@ -577,8 +569,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -607,10 +599,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -641,11 +631,11 @@
     /* The addition is safe here since the ticket length is 16 bit. */
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 + tlen );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SESSION_TICKET );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SESSION_TICKET );
 
-    *p++ = (unsigned char)( ( tlen >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( tlen      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( tlen );
+    *p++ = MBEDTLS_CHAR_0( tlen );
 
     *olen = 4;
 
@@ -685,8 +675,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 + alpnlen );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ALPN );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ALPN );
 
     /*
      * opaque ProtocolName<1..2^8-1>;
@@ -713,12 +703,12 @@
     *olen = p - buf;
 
     /* List length = olen - 2 (ext_type) - 2 (ext_len) - 2 (list_len) */
-    buf[4] = (unsigned char)( ( ( *olen - 6 ) >> 8 ) & 0xFF );
-    buf[5] = (unsigned char)( ( ( *olen - 6 )      ) & 0xFF );
+    buf[4] = MBEDTLS_CHAR_1( *olen - 6 );
+    buf[5] = MBEDTLS_CHAR_0( *olen - 6 );
 
     /* Extension length = olen - 2 (ext_type) - 2 (ext_len) */
-    buf[2] = (unsigned char)( ( ( *olen - 4 ) >> 8 ) & 0xFF );
-    buf[3] = (unsigned char)( ( ( *olen - 4 )      ) & 0xFF );
+    buf[2] = MBEDTLS_CHAR_1( *olen - 4 );
+    buf[3] = MBEDTLS_CHAR_0( *olen - 4 );
 
     return( 0 );
 }
@@ -770,12 +760,12 @@
      */
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, ext_len + 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_USE_SRTP );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_USE_SRTP );
 
 
-    *p++ = (unsigned char)( ( ( ext_len & 0xFF00 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ext_len & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( ext_len & 0xFF00 );
+    *p++ = MBEDTLS_CHAR_0( ext_len );
 
     /* protection profile length: 2*(ssl->conf->dtls_srtp_profile_list_len) */
     /* micro-optimization:
@@ -786,8 +776,7 @@
      *                        >> 8 ) & 0xFF );
      */
     *p++ = 0;
-    *p++ = (unsigned char)( ( 2 * ssl->conf->dtls_srtp_profile_list_len )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_0( 2 * ssl->conf->dtls_srtp_profile_list_len );
 
     for( protection_profiles_index=0;
          protection_profiles_index < ssl->conf->dtls_srtp_profile_list_len;
@@ -799,8 +788,8 @@
         {
             MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_write_use_srtp_ext, add profile: %04x",
                                         profile_value ) );
-            *p++ = ( ( profile_value >> 8 ) & 0xFF );
-            *p++ = ( profile_value & 0xFF );
+            *p++ = MBEDTLS_BYTE_1( profile_value );
+            *p++ = MBEDTLS_BYTE_0( profile_value );
         }
         else
         {
@@ -1334,8 +1323,8 @@
     {
         /* No need to check for space here, because the extension
          * writing functions already took care of that. */
-        *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_1( ext_len );
+        *p++ = MBEDTLS_CHAR_0( ext_len );
         p += ext_len;
     }