diff --git a/dix/events.c b/dix/events.c
index 98ea15b5ba72a503f25ac523cceb8625c135ae96..f546700fabc933037d1df0ad55dd1296b96c180e 100644
--- a/dix/events.c
+++ b/dix/events.c
@@ -597,6 +597,8 @@ XineramaConfineCursorToWindow(DeviceIntPtr pDev,
 
     int x, y, off_x, off_y, i;
 
+    assert(!noPanoramiXExtension);
+
     if (!XineramaSetWindowPntrs(pDev, pWin))
         return;