diff --git a/py_gen/templates/message.py b/py_gen/templates/message.py
index ffad6cf..8bf11f1 100644
--- a/py_gen/templates/message.py
+++ b/py_gen/templates/message.py
@@ -28,6 +28,7 @@
 :: import itertools
 :: import of_g
 :: import py_gen.util as util
+:: import py_gen.oftype
 :: include('_copyright.py')
 
 :: include('_autogen.py')
@@ -66,7 +67,7 @@
         if ${m.name} != None:
             self.${m.name} = ${m.name}
         else:
-            self.${m.name} = ${m.oftype.gen_init_expr()}
+            self.${m.name} = ${py_gen.oftype.gen_init_expr(m.oftype)}
 :: #endfor
 
     def pack(self):