diff --git a/utest/test_frontend.py b/utest/test_frontend.py
index 7af5121..2119363 100755
--- a/utest/test_frontend.py
+++ b/utest/test_frontend.py
@@ -85,20 +85,20 @@
                 ['OFPPC_NO_PACKET_IN', 64]]],
             ['metadata', 'version', '2'],
             ['struct', 'of_echo_reply', [
-                ['uint8_t', 'version'],
-                ['uint8_t', 'type'],
-                ['uint16_t', 'length'],
-                ['uint32_t', 'xid'],
-                ['of_octets_t', 'data']]],
+                ['data', 'uint8_t', 'version'],
+                ['data', 'uint8_t', 'type'],
+                ['data', 'uint16_t', 'length'],
+                ['data', 'uint32_t', 'xid'],
+                ['data', 'of_octets_t', 'data']]],
             ['enum', 'ofp_queue_op_failed_code', [
                 ['OFPQOFC_BAD_PORT', 0],
                 ['OFPQOFC_BAD_QUEUE', 1],
                 ['OFPQOFC_EPERM', 2]]],
             ['struct', 'of_packet_queue', [
-                ['uint32_t', 'queue_id'],
-                ['uint16_t', 'len'],
+                ['data', 'uint32_t', 'queue_id'],
+                ['data', 'uint16_t', 'len'],
                 ['pad', 2],
-                ['list(of_queue_prop_t)', 'properties']]],
+                ['data', 'list(of_queue_prop_t)', 'properties']]],
         ]
         self.assertEquals(expected_ast, ast)
 
diff --git a/utest/test_parser.py b/utest/test_parser.py
index da262a4..a4a0e63 100755
--- a/utest/test_parser.py
+++ b/utest/test_parser.py
@@ -46,7 +46,7 @@
 """
         ast = parser.parse(src)
         self.assertEquals(ast,
-            [['struct', 'foo', [['uint32_t', 'bar']]]])
+            [['struct', 'foo', [['data', 'uint32_t', 'bar']]]])
 
     def test_multiple_fields(self):
         src = """\
@@ -59,9 +59,9 @@
         ast = parser.parse(src)
         self.assertEquals(ast,
             [['struct', 'foo',
-                [['uint32_t', 'bar'],
-                 ['uint8_t', 'baz'],
-                 ['uint64_t', 'abc']]]])
+                [['data', 'uint32_t', 'bar'],
+                 ['data', 'uint8_t', 'baz'],
+                 ['data', 'uint64_t', 'abc']]]])
 
     def test_array_type(self):
         src = """\
@@ -71,7 +71,7 @@
 """
         ast = parser.parse(src)
         self.assertEquals(ast,
-            [['struct', 'foo', [['uint32_t[4]', 'bar']]]])
+            [['struct', 'foo', [['data', 'uint32_t[4]', 'bar']]]])
 
     def test_list_type(self):
         src = """\
@@ -81,7 +81,7 @@
 """
         ast = parser.parse(src)
         self.assertEquals(ast,
-            [['struct', 'foo', [['list(of_action_t)', 'bar']]]])
+            [['struct', 'foo', [['data', 'list(of_action_t)', 'bar']]]])
 
     def test_pad_type(self):
         src = """\
@@ -163,7 +163,7 @@
 """
         ast = parser.parse(src)
         self.assertEquals(ast,
-            [['struct', 'foo', [['uint32_t', 'a']]]])
+            [['struct', 'foo', [['data', 'uint32_t', 'a']]]])
 
     def test_mixed(self):
         src = """\