diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c
index 3437302dd1..a3da80f888 100644
--- a/src/qemu/qemu_block.c
+++ b/src/qemu/qemu_block.c
@@ -272,13 +272,13 @@ qemuBlockDiskDetectNodes(virDomainDiskDefPtr disk,
     qemuBlockNodeNameBackingChainDataPtr entry = NULL;
     virStorageSourcePtr src = disk->src;
 
-    if (!(entry = virHashLookup(disktable, disk->info.alias)))
-        return 0;
-
     /* don't attempt the detection if the top level already has node names */
     if (src->nodeformat || src->nodestorage)
         return 0;
 
+    if (!(entry = virHashLookup(disktable, disk->info.alias)))
+        return 0;
+
     while (src && entry) {
         if (src->nodeformat || src->nodestorage) {
             if (STRNEQ_NULLABLE(src->nodeformat, entry->nodeformat) ||