diff --git a/lib/ftp.c b/lib/ftp.c
index 4a1e3d6421..f763b183b1 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -151,6 +151,7 @@ static void _ftp_state(struct Curl_easy *data,
   )
 {
 #if defined(CURL_DISABLE_VERBOSE_STRINGS)
+  (void)data;
 #ifdef DEBUGBUILD
   (void)lineno;
 #endif