diff --git a/lib/config.py b/lib/config.py
index f5f9ea025788c7856ec3323a8f6757a08db21bde..3b9c3d47ae30bb19c4946bbea45411f106c7509a 100644
--- a/lib/config.py
+++ b/lib/config.py
@@ -617,7 +617,7 @@ class ConfigWriter:
 
     """
     self._OpenConfig()
-    self._config_data.cluster["volume_group_name"] = vg_name
+    self._config_data.cluster.volume_group_name = vg_name
     self._WriteConfig()
 
   def GetDefBridge(self):