diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index 8aba27a71d..3e3af30c08 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -364,9 +364,13 @@ cbw_child_perm(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role,
                            perm, shared, nperm, nshared);
 
         if (!QLIST_EMPTY(&bs->parents)) {
-            if (perm & BLK_PERM_WRITE) {
-                *nperm = *nperm | BLK_PERM_CONSISTENT_READ;
-            }
+            /*
+             * Note, that source child may be shared with backup job. Backup job
+             * does create own blk parent on copy-before-write node, so this
+             * works even if source node does not have any parents before backup
+             * start
+             */
+            *nperm = *nperm | BLK_PERM_CONSISTENT_READ;
             *nshared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
         }
     }