diff --git a/dix/devices.c b/dix/devices.c
index 62ff4b04c..f5d295295 100644
--- a/dix/devices.c
+++ b/dix/devices.c
@@ -2341,7 +2341,7 @@ RecalculateMasterButtons(DeviceIntPtr slave)
         maxbuttons = max(maxbuttons, dev->button->numButtons);
     }
 
-    if (master->button->numButtons != maxbuttons)
+    if (master->button && master->button->numButtons != maxbuttons)
     {
         int i;
         DeviceChangedEvent event;