diff --git a/scst/src/scst_copy_mgr.c b/scst/src/scst_copy_mgr.c
index cba7f11ce..eda4dfd6a 100644
--- a/scst/src/scst_copy_mgr.c
+++ b/scst/src/scst_copy_mgr.c
@@ -2676,12 +2676,17 @@ out:
 
 void scst_cm_update_dev(struct scst_device *dev)
 {
+	unsigned int lun;
 	int rc, res;
 
 	TRACE_ENTRY();
 
 	TRACE_MGMT_DBG("copy manager: updating device %s", dev->virt_name);
 
+	if (!scst_auto_cm_assignment ||
+	    !dev->handler->auto_cm_assignment_possible)
+		goto out;
+
 	res = scst_suspend_activity(SCST_SUSPEND_TIMEOUT_UNLIMITED);
 	WARN_ON_ONCE(res);
 
@@ -2693,7 +2698,11 @@ void scst_cm_update_dev(struct scst_device *dev)
 	scst_block_dev(dev);
 	spin_unlock_bh(&dev->dev_lock);
 
-	rc = scst_cm_send_init_inquiry(dev, scst_cm_get_lun(dev), NULL);
+	lun = scst_cm_get_lun(dev);
+	if (WARN_ON_ONCE(lun == SCST_MAX_LUN))
+		goto out_unblock;
+
+	rc = scst_cm_send_init_inquiry(dev, lun, NULL);
 	if (rc != 0)
 		goto out_unblock;
 
@@ -2701,6 +2710,7 @@ out_resume:
 	mutex_unlock(&scst_mutex);
 	scst_resume_activity();
 
+out:
 	TRACE_EXIT();
 	return;