diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 8467b13..341eb7d 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1293,14 +1293,17 @@
         defined(MBEDTLS_SSL_PROTO_TLS1_2)
         if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
         {
+            unsigned char mac[MBEDTLS_SSL_MAC_ADD];
+
             mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, ssl->out_ctr, 8 );
             mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, ssl->out_hdr, 3 );
             mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, ssl->out_len, 2 );
             mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc,
                              ssl->out_msg, ssl->out_msglen );
-            mbedtls_md_hmac_finish( &ssl->transform_out->md_ctx_enc,
-                             ssl->out_msg + ssl->out_msglen );
+            mbedtls_md_hmac_finish( &ssl->transform_out->md_ctx_enc, mac );
             mbedtls_md_hmac_reset( &ssl->transform_out->md_ctx_enc );
+
+            memcpy( ssl->out_msg + ssl->out_msglen, mac, ssl->transform_out->maclen );
         }
         else
 #endif
@@ -1562,8 +1565,6 @@
     return( 0 );
 }
 
-#define SSL_MAX_MAC_SIZE   48
-
 static int ssl_decrypt_buf( mbedtls_ssl_context *ssl )
 {
     size_t i;
@@ -1731,7 +1732,7 @@
 #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
         if( ssl->session_in->encrypt_then_mac == MBEDTLS_SSL_ETM_ENABLED )
         {
-            unsigned char computed_mac[SSL_MAX_MAC_SIZE];
+            unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
             unsigned char pseudo_hdr[13];
 
             MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
@@ -1749,16 +1750,16 @@
             mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, pseudo_hdr, 13 );
             mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec,
                              ssl->in_iv, ssl->in_msglen );
-            mbedtls_md_hmac_finish( &ssl->transform_in->md_ctx_dec, computed_mac );
+            mbedtls_md_hmac_finish( &ssl->transform_in->md_ctx_dec, mac_expect );
             mbedtls_md_hmac_reset( &ssl->transform_in->md_ctx_dec );
 
             MBEDTLS_SSL_DEBUG_BUF( 4, "message  mac", ssl->in_iv + ssl->in_msglen,
                                               ssl->transform_in->maclen );
-            MBEDTLS_SSL_DEBUG_BUF( 4, "computed mac", computed_mac,
+            MBEDTLS_SSL_DEBUG_BUF( 4, "expected mac", mac_expect,
                                               ssl->transform_in->maclen );
 
-            if( mbedtls_ssl_safer_memcmp( ssl->in_iv + ssl->in_msglen, computed_mac,
-                              ssl->transform_in->maclen ) != 0 )
+            if( mbedtls_ssl_safer_memcmp( ssl->in_iv + ssl->in_msglen, mac_expect,
+                                          ssl->transform_in->maclen ) != 0 )
             {
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
 
@@ -1918,15 +1919,13 @@
 #if defined(SSL_SOME_MODES_USE_MAC)
     if( auth_done == 0 )
     {
-        unsigned char tmp[SSL_MAX_MAC_SIZE];
+        unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
 
         ssl->in_msglen -= ssl->transform_in->maclen;
 
         ssl->in_len[0] = (unsigned char)( ssl->in_msglen >> 8 );
         ssl->in_len[1] = (unsigned char)( ssl->in_msglen      );
 
-        memcpy( tmp, ssl->in_msg + ssl->in_msglen, ssl->transform_in->maclen );
-
 #if defined(MBEDTLS_SSL_PROTO_SSL3)
         if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
         {
@@ -1965,8 +1964,7 @@
             mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_len, 2 );
             mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_msg,
                              ssl->in_msglen );
-            mbedtls_md_hmac_finish( &ssl->transform_in->md_ctx_dec,
-                             ssl->in_msg + ssl->in_msglen );
+            mbedtls_md_hmac_finish( &ssl->transform_in->md_ctx_dec, mac_expect );
             /* Call mbedtls_md_process at least once due to cache attacks */
             for( j = 0; j < extra_run + 1; j++ )
                 mbedtls_md_process( &ssl->transform_in->md_ctx_dec, ssl->in_msg );
@@ -1981,12 +1979,12 @@
             return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
         }
 
-        MBEDTLS_SSL_DEBUG_BUF( 4, "message  mac", tmp, ssl->transform_in->maclen );
-        MBEDTLS_SSL_DEBUG_BUF( 4, "computed mac", ssl->in_msg + ssl->in_msglen,
-                       ssl->transform_in->maclen );
+        MBEDTLS_SSL_DEBUG_BUF( 4, "expected mac", mac_expect, ssl->transform_in->maclen );
+        MBEDTLS_SSL_DEBUG_BUF( 4, "message  mac", ssl->in_msg + ssl->in_msglen,
+                               ssl->transform_in->maclen );
 
-        if( mbedtls_ssl_safer_memcmp( tmp, ssl->in_msg + ssl->in_msglen,
-                         ssl->transform_in->maclen ) != 0 )
+        if( mbedtls_ssl_safer_memcmp( ssl->in_msg + ssl->in_msglen, mac_expect,
+                                      ssl->transform_in->maclen ) != 0 )
         {
 #if defined(MBEDTLS_SSL_DEBUG_ALL)
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );