diff --git a/xkb/xkbActions.c b/xkb/xkbActions.c
index 64e17e9ac..aea479cd1 100644
--- a/xkb/xkbActions.c
+++ b/xkb/xkbActions.c
@@ -1075,7 +1075,7 @@ int		button;
 	switch (filter->upAction.type) {
 	    case XkbSA_LockDeviceBtn:
 		if ((filter->upAction.devbtn.flags&XkbSA_LockNoUnlock)||
-		    BitIsOn(dev->button->down, button))
+		    !BitIsOn(dev->button->down, button))
 		    return 0;
 		XkbDDXFakeDeviceButton(dev,False,button);
 		break;