diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index fdd1a71..a3212cc 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2142,6 +2142,7 @@
     if( auth_done == 0 )
     {
         unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
+        unsigned char mac_peer[MBEDTLS_SSL_MAC_ADD];
 
         ssl->in_msglen -= ssl->transform_in->maclen;
 
@@ -2156,6 +2157,8 @@
                       ssl->in_msg, ssl->in_msglen,
                       ssl->in_ctr, ssl->in_msgtype,
                       mac_expect );
+            memcpy( mac_peer, ssl->in_msg + ssl->in_msglen,
+                              ssl->transform_in->maclen );
         }
         else
 #endif /* MBEDTLS_SSL_PROTO_SSL3 */
@@ -2200,6 +2203,8 @@
              * attacks much tighter and hopefully impractical. */
             ssl_read_memory( ssl->in_msg + min_len,
                                  max_len - min_len + ssl->transform_in->maclen );
+            memcpy( mac_peer, ssl->in_msg + ssl->in_msglen,
+                              ssl->transform_in->maclen );
         }
         else
 #endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
@@ -2211,11 +2216,10 @@
 
 #if defined(MBEDTLS_SSL_DEBUG_ALL)
         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 );
+        MBEDTLS_SSL_DEBUG_BUF( 4, "message  mac", mac_peer, ssl->transform_in->maclen );
 #endif
 
-        if( mbedtls_ssl_safer_memcmp( ssl->in_msg + ssl->in_msglen, mac_expect,
+        if( mbedtls_ssl_safer_memcmp( mac_peer, mac_expect,
                                       ssl->transform_in->maclen ) != 0 )
         {
 #if defined(MBEDTLS_SSL_DEBUG_ALL)