diff --git a/src/gui_at_sb.c b/src/gui_at_sb.c
index 16d8d36..6cf1e7b 100644
--- a/src/gui_at_sb.c
+++ b/src/gui_at_sb.c
@@ -820,7 +820,7 @@
     if (mode == SMODE_PAGE_UP || mode == SMODE_LINE_UP)
 	call_data = -call_data;
 
-    XtCallCallbacks((Widget)sbw, XtNscrollProc, (XtPointer)call_data);
+    XtCallCallbacks((Widget)sbw, XtNscrollProc, (XtPointer)(long_u)call_data);
 
     sbw->scrollbar.timer_id =
 	XtAppAddTimeOut(XtWidgetToApplicationContext((Widget)sbw),
@@ -894,7 +894,7 @@
 	return;
 
     sbw->scrollbar.scroll_mode = SMODE_LINE_UP;
-    XtCallCallbacks(w, XtNscrollProc, (XtPointer)call_data);
+    XtCallCallbacks(w, XtNscrollProc, (XtPointer)(long_u)call_data);
 }
 
     static void
@@ -977,7 +977,7 @@
     }
 
     if (call_data)
-	XtCallCallbacks(w, XtNscrollProc, (XtPointer)call_data);
+	XtCallCallbacks(w, XtNscrollProc, (XtPointer)(long_u)call_data);
 
     /* establish autoscroll */
     if (delay)