diff --git a/lib/cmdlib.py b/lib/cmdlib.py
index ca7ff6816e66b205526b9ff407205d385b936d26..35093f4ba0e635cbe6b7ea8acd2a3112795c5b9e 100644
--- a/lib/cmdlib.py
+++ b/lib/cmdlib.py
@@ -4284,7 +4284,7 @@ class LUSetInstanceParams(LogicalUnit):
       instance.vnc_bind_address = self.vnc_bind_address
       result.append(("vnc_bind_address", self.vnc_bind_address))
 
-    self.cfg.AddInstance(instance)
+    self.cfg.Update(instance)
 
     return result