diff --git a/api-daemon/pvcapid/helper.py b/api-daemon/pvcapid/helper.py
index 4a628f69..9d4614da 100755
--- a/api-daemon/pvcapid/helper.py
+++ b/api-daemon/pvcapid/helper.py
@@ -102,7 +102,7 @@ def backup_cluster(zkhandler):
 
     get_data('/')
 
-    return cluster_data, 200
+    return json.dumps(cluster_data), 200
 
 
 @ZKConnection(config)