diff --git a/lib/cmdlib.py b/lib/cmdlib.py
index 4a7e663759f4a2cd489ff7492d7e3cb4da1a5cc9..b133cc50f13d9c1a0f50beade7d265bad6a67131 100644
--- a/lib/cmdlib.py
+++ b/lib/cmdlib.py
@@ -15865,8 +15865,8 @@ class LUNetworkAdd(LogicalUnit):
     uuid = self.cfg.LookupNetwork(self.op.network_name)
 
     if uuid:
-      raise errors.OpPrereqError("Network '%s' already defined" %
-                                 self.op.network, errors.ECODE_EXISTS)
+      raise errors.OpPrereqError(("Network with name '%s' already exists" %
+                                  self.op.network_name), errors.ECODE_EXISTS)
 
     # Check tag validity
     for tag in self.op.tags: