diff --git a/py_gen/templates/_ofclass.py b/py_gen/templates/_ofclass.py
index c84ceea..f902ae8 100644
--- a/py_gen/templates/_ofclass.py
+++ b/py_gen/templates/_ofclass.py
@@ -28,7 +28,7 @@
         return ''.join(packed)
 
     @staticmethod
-    def unpack(buf):
+    def unpack(reader):
         obj = ${ofclass.pyname}()
 :: include("_unpack.py", ofclass=ofclass)
         return obj