diff --git a/Lib/lib-stdwin/WindowSched.py b/Lib/lib-stdwin/WindowSched.py
index 19be2b1..8c9151c 100644
--- a/Lib/lib-stdwin/WindowSched.py
+++ b/Lib/lib-stdwin/WindowSched.py
@@ -22,7 +22,8 @@
 	# Use millisleep for very short delays or if there are no windows
 	#
 	if msecs < 100 or WindowParent.CountWindows() = 0:
-		time.millisleep(msecs)
+		if msecs > 0:
+			time.millisleep(msecs)
 		return
 	#
 	# Post a timer event on an arbitrary window and wait for it