Index: uspace/lib/drv/generic/driver.c
===================================================================
--- uspace/lib/drv/generic/driver.c	(revision f480d7e1f5cf4ba7a6678d2d63060e7f8756330d)
+++ uspace/lib/drv/generic/driver.c	(revision b29bb098aa093f6015e148a9c216b7fcd225b8d6)
@@ -313,5 +313,6 @@
 	fibril_mutex_lock(&devices_mutex);
 	dev = driver_get_device(devh);
-	dev_add_ref(dev);
+	if (dev != NULL)
+		dev_add_ref(dev);
 	fibril_mutex_unlock(&devices_mutex);