diff --git a/include/polarssl/ssl.h b/include/polarssl/ssl.h
index 6b5124d..6570081 100644
--- a/include/polarssl/ssl.h
+++ b/include/polarssl/ssl.h
@@ -455,6 +455,7 @@
     unsigned char key_name[16];     /*!< name to quickly discard bad tickets */
     aes_context enc;                /*!< encryption context                  */
     aes_context dec;                /*!< decryption context                  */
+    unsigned char mac_key[16];      /*!< authentication key                  */
 };
 
 struct _ssl_context