diff --git a/src/gui_motif.c b/src/gui_motif.c
index 72a2915..3d77b82 100644
--- a/src/gui_motif.c
+++ b/src/gui_motif.c
@@ -118,7 +118,7 @@
  */
 
     static void
-scroll_cb(Widget w UNUSED, XtPointer client_data, call_data)
+scroll_cb(Widget w UNUSED, XtPointer client_data, XtPointer call_data)
 {
     scrollbar_T *sb;
     long	value;