diff --git a/tools/munger/scripts/error_gen.py b/tools/munger/scripts/error_gen.py
index c8f4bf2..512a567 100644
--- a/tools/munger/scripts/error_gen.py
+++ b/tools/munger/scripts/error_gen.py
@@ -39,6 +39,7 @@
         ofp_error_msg.__init__(self)
         self.version = OFP_VERSION
         self.type = OFPT_ERROR
+        self.xid = None
         self.err_type = --ERROR_NAME--
         self.data = ""