diff --git a/src/mouse.c b/src/mouse.c
index 954b213..4e8dd4d 100644
--- a/src/mouse.c
+++ b/src/mouse.c
@@ -2234,7 +2234,7 @@
 static int	held_button = MOUSE_RELEASE;
 
     void
-reset_held_button()
+reset_held_button(void)
 {
     held_button = MOUSE_RELEASE;
 }