Index: uspace/lib/drv/generic/driver.c
===================================================================
--- uspace/lib/drv/generic/driver.c	(revision 224c0e7cdf71623ced2dfae1613f0f4c6f94d45b)
+++ uspace/lib/drv/generic/driver.c	(revision bbd4c725136443faef2d5737a2b6387fb04f81c1)
@@ -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);