Use our habitual INTERNAL_ERROR debug message
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 893429d..8e855a1 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2043,7 +2043,7 @@
                     break;
 #endif
                 default:
-                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "unsupported HMAC hash" ) );
+                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
                     return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
             }