diff --git a/py_gen/templates/_ofclass.py b/py_gen/templates/_ofclass.py
index 4c5358e..ec6b04e 100644
--- a/py_gen/templates/_ofclass.py
+++ b/py_gen/templates/_ofclass.py
@@ -1,4 +1,5 @@
 :: from loxi_ir import *
+:: import py_gen.oftype
 :: normal_members = [m for m in ofclass.members if type(m) == OFDataMember]
 class ${ofclass.pyname}(${superclass}):
 :: for m in ofclass.type_members:
@@ -10,7 +11,7 @@
         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
         return
 
diff --git a/py_gen/templates/_pack.py b/py_gen/templates/_pack.py
index 9a481b2..4714e97 100644
--- a/py_gen/templates/_pack.py
+++ b/py_gen/templates/_pack.py
@@ -27,6 +27,7 @@
 ::
 :: # TODO coalesce format strings
 :: from loxi_ir import *
+:: from py_gen.oftype import gen_pack_expr
 :: length_member = None
 :: length_member_index = None
 :: field_length_members = {}
@@ -36,26 +37,26 @@
 ::     if type(m) == OFLengthMember:
 ::         length_member = m
 ::         length_member_index = index
-        packed.append(${m.oftype.gen_pack_expr('0')}) # placeholder for ${m.name} at index ${index}
+        packed.append(${gen_pack_expr(m.oftype, '0')}) # placeholder for ${m.name} at index ${index}
 ::     elif type(m) == OFFieldLengthMember:
 ::         field_length_members[m.field_name] = m
 ::         field_length_indexes[m.field_name] = index
-        packed.append(${m.oftype.gen_pack_expr('0')}) # placeholder for ${m.name} at index ${index}
+        packed.append(${gen_pack_expr(m.oftype, '0')}) # placeholder for ${m.name} at index ${index}
 ::     elif type(m) == OFPadMember:
         packed.append('\x00' * ${m.length})
 ::     else:
-        packed.append(${m.oftype.gen_pack_expr('self.' + m.name)})
+        packed.append(${gen_pack_expr(m.oftype, 'self.' + m.name)})
 ::         if m.name in field_length_members:
 ::             field_length_member = field_length_members[m.name]
 ::             field_length_index = field_length_indexes[m.name]
-        packed[${field_length_index}] = ${field_length_member.oftype.gen_pack_expr('len(packed[-1])')}
+        packed[${field_length_index}] = ${gen_pack_expr(field_length_member.oftype, 'len(packed[-1])')}
 ::         #endif
 ::     #endif
 ::     index += 1
 :: #endfor
 :: if length_member_index != None:
         length = sum([len(x) for x in packed])
-        packed[${length_member_index}] = ${length_member.oftype.gen_pack_expr('length')}
+        packed[${length_member_index}] = ${gen_pack_expr(length_member.oftype, 'length')}
 :: #endif
 :: if ofclass.name == 'of_match_v3':
         packed.append('\x00' * ((length + 7)/8*8 - length))
diff --git a/py_gen/templates/_pretty_print.py b/py_gen/templates/_pretty_print.py
index 65c5941..7be7a14 100644
--- a/py_gen/templates/_pretty_print.py
+++ b/py_gen/templates/_pretty_print.py
@@ -44,15 +44,15 @@
                     q.text("%#x" % self.${m.name})
                 else:
                     q.text('None')
-:: elif m.oftype.base == 'of_mac_addr_t':
+:: elif m.oftype == 'of_mac_addr_t':
                 q.text(util.pretty_mac(self.${m.name}))
-:: elif m.oftype.base == 'uint32_t' and m.name.startswith("ipv4"):
+:: elif m.oftype == 'uint32_t' and m.name.startswith("ipv4"):
                 q.text(util.pretty_ipv4(self.${m.name}))
-:: elif m.oftype.base == 'of_wc_bmap_t' and version in [1,2]:
+:: elif m.oftype == 'of_wc_bmap_t' and version in [1,2]:
                 q.text(util.pretty_wildcards(self.${m.name}))
-:: elif m.oftype.base == 'of_port_no_t':
+:: elif m.oftype == 'of_port_no_t':
                 q.text(util.pretty_port(self.${m.name}))
-:: elif m.oftype.base.startswith("uint"):
+:: elif m.oftype.startswith("uint"):
                 q.text("%#x" % self.${m.name})
 :: else:
                 q.pp(self.${m.name})
diff --git a/py_gen/templates/_unpack.py b/py_gen/templates/_unpack.py
index 211043e..133e831 100644
--- a/py_gen/templates/_unpack.py
+++ b/py_gen/templates/_unpack.py
@@ -27,6 +27,7 @@
 ::
 :: # TODO coalesce format strings
 :: from loxi_ir import *
+:: from py_gen.oftype import gen_unpack_expr
         if type(buf) == loxi.generic_util.OFReader:
             reader = buf
         else:
@@ -36,12 +37,12 @@
 ::     if type(m) == OFPadMember:
         reader.skip(${m.length})
 ::     elif type(m) == OFLengthMember:
-        _${m.name} = ${m.oftype.gen_unpack_expr('reader')}
+        _${m.name} = ${gen_unpack_expr(m.oftype, 'reader')}
 ::     elif type(m) == OFFieldLengthMember:
 ::         field_length_members[m.field_name] = m
-        _${m.name} = ${m.oftype.gen_unpack_expr('reader')}
+        _${m.name} = ${gen_unpack_expr(m.oftype, 'reader')}
 ::     elif type(m) == OFTypeMember:
-        _${m.name} = ${m.oftype.gen_unpack_expr('reader')}
+        _${m.name} = ${gen_unpack_expr(m.oftype, 'reader')}
         assert(_${m.name} == ${m.value})
 ::     elif type(m) == OFDataMember:
 ::         if m.name in field_length_members:
@@ -49,7 +50,7 @@
 ::         else:
 ::             reader_expr = 'reader'
 ::         #endif
-        obj.${m.name} = ${m.oftype.gen_unpack_expr(reader_expr)}
+        obj.${m.name} = ${gen_unpack_expr(m.oftype, reader_expr)}
 ::     #endif
 :: #endfor
 :: if ofclass.name == 'of_match_v3':
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):
diff --git a/py_gen/templates/oxm.py b/py_gen/templates/oxm.py
index 2a10a5f..d95dd8e 100644
--- a/py_gen/templates/oxm.py
+++ b/py_gen/templates/oxm.py
@@ -27,6 +27,7 @@
 ::
 :: import itertools
 :: import of_g
+:: import py_gen.oftype
 :: include('_copyright.py')
 
 :: include('_autogen.py')
@@ -65,7 +66,7 @@
         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):