diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 0522778..ec84047 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -307,6 +307,9 @@
                                               resending messages             */
     unsigned char alt_out_ctr[8];       /*!<  Alternative record epoch/counter
                                               for resending messages         */
+
+    uint8_t seen_ccs;                   /*!< Indicates if a CCS message has
+                                         *   been seen in the current flight. */
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
     /*