diff --git a/src/windows.c b/src/windows.c
index 069f6d3df..0632a09b3 100644
--- a/src/windows.c
+++ b/src/windows.c
@@ -1326,7 +1326,7 @@ winid win UNUSED;
 static void
 dump_start_menu(win, mbehavior)
 winid win UNUSED;
-unsigned long mbehavior;
+unsigned long mbehavior UNUSED;
 {
     return;
 }