diff --git a/drivers/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
index 93b2862bd3faecbc5702759855db207c43c49f17..674d848e377c8e0e5876c2b663980168950e122f 100644
--- a/drivers/s390/cio/ccwgroup.c
+++ b/drivers/s390/cio/ccwgroup.c
@@ -372,7 +372,7 @@ int ccwgroup_create_dev(struct device *parent, struct ccwgroup_driver *gdrv,
 		goto error;
 	}
 	/* Check for trailing stuff. */
-	if (i == num_devices && strlen(buf) > 0) {
+	if (i == num_devices && buf && strlen(buf) > 0) {
 		rc = -EINVAL;
 		goto error;
 	}