diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 4abf02a208..8dbae7aaa5 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1857,7 +1857,7 @@ int mbedtls_ssl_psk_derive_premaster( mbedtls_ssl_context *ssl, mbedtls_key_exch
          * This should never happen because the existence of a PSK is always
          * checked before calling this function
          */
-        MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
 
     /*
      * PMS = struct {