diff --git a/x11/pdcdisp.c b/x11/pdcdisp.c
index af5d70a0..79e75439 100644
--- a/x11/pdcdisp.c
+++ b/x11/pdcdisp.c
@@ -433,5 +433,5 @@ void PDC_transform_line(int lineno, int x, int len, const chtype *srcp)
 
 void PDC_doupdate(void)
 {
-    XFlush(XtDisplay(pdc_toplevel));
+    XSync(XtDisplay(pdc_toplevel), False);
 }