diff --git a/include/linux/mISDNif.h b/include/linux/mISDNif.h
index 557477ac3d5b..5da3d95b27f1 100644
--- a/include/linux/mISDNif.h
+++ b/include/linux/mISDNif.h
@@ -559,7 +559,10 @@ extern void	mISDN_unregister_clock(struct mISDNclock *);
 
 static inline struct mISDNdevice *dev_to_mISDN(struct device *dev)
 {
-	return dev_get_drvdata(dev);
+	if (dev)
+		return dev_get_drvdata(dev);
+	else
+		return NULL;
 }
 
 extern void	set_channel_address(struct mISDNchannel *, u_int, u_int);