$NetBSD$

--- src/mouse.c.orig	2008-03-20 19:55:51 +0100
+++ src/mouse.c
@@ -2464,6 +2464,10 @@ MousePostEvent(InputInfoPtr pInfo, int t
     if (mousepriv) {
 	mousepriv->fracdx += mousepriv->sensitivity*dx;
 	mousepriv->fracdy += mousepriv->sensitivity*dy;
+	if (isnan(mousepriv->fracdx))
+		mousepriv->fracdx = 0;
+	if (isnan(mousepriv->fracdy))
+		mousepriv->fracdy = 0;
 	mousepriv->fracdx -= ( dx=(int)(mousepriv->fracdx) );
 	mousepriv->fracdy -= ( dy=(int)(mousepriv->fracdy) );
     }