diff --git a/pfp/interp.py b/pfp/interp.py
index b495cce..49e938d 100644
--- a/pfp/interp.py
+++ b/pfp/interp.py
@@ -52,7 +52,9 @@ def _pfp__init(self, stream):
             self._pfp__node.args, scope, self, None
         )
         param_list = params.instantiate(scope, struct_args, self._pfp__interp)
-        super(self.__class__, self)._pfp__init(stream)
+
+        if hasattr(super(self.__class__, self), "_pfp__init"):
+            super(self.__class__, self)._pfp__init(stream)
 
     new_class = type(
         struct_cls.__name__ + "_", (struct_cls,), {"_pfp__init": _pfp__init}
@@ -84,13 +86,28 @@ def StructUnionTypeRef(curr_scope, typedef_name, refd_name, interp, node):
     elif isinstance(node, AST.Union):
         cls = fields.Union
 
-    def __new__(self, *args, **kwargs):
+    def __new__(cls_, *args, **kwargs):
         refd_type = curr_scope.get_type(refd_name)
         if refd_type is None:
             refd_node = node
         else:
             refd_node = refd_type._pfp__node
-        return StructUnionDef(typedef_name, interp, refd_node)(*args, **kwargs)
+
+        def merged_init(self, stream):
+            if six.PY3:
+                cls_._pfp__init(self, stream)
+            else:
+                cls_._pfp__init.__func__(self, stream)
+            self._pfp__init_orig(stream)
+
+        overrides = {}
+        if hasattr(cls_, "_pfp__init"):
+            overrides["_pfp__init"] = merged_init
+
+        res = base_cls = StructUnionDef(
+            typedef_name, interp, refd_node, overrides=overrides,
+        )
+        return res(*args, **kwargs)
 
     new_class = type(
         typedef_name,
@@ -102,13 +119,16 @@ def __new__(self, *args, **kwargs):
     return new_class
 
 
-
-def StructUnionDef(typedef_name, interp, node):
+def StructUnionDef(typedef_name, interp, node, overrides=None, cls=None):
+    if overrides is None:
+        overrides = {}
     if isinstance(node, AST.Struct):
-        cls = fields.Struct
+        if cls is None:
+            cls = fields.Struct
         decls = StructDecls(node.decls, node.coord)
     elif isinstance(node, AST.Union):
-        cls = fields.Union
+        if cls is None:
+            cls = fields.Union
         decls = UnionDecls(node.decls, node.coord)
 
     # this is so that we can have all nested structs added to
@@ -117,7 +137,11 @@ def StructUnionDef(typedef_name, interp, node):
     # the new struct to not be added to its parent, and the user would
     # not be able to see how far the script got
     def __init__(self, stream=None, metadata_processor=None, do_init=True):
-        cls.__init__(self, stream, metadata_processor=metadata_processor)
+        cls.__init__(
+            self,
+            stream,
+            metadata_processor=metadata_processor,
+        )
 
         if do_init:
             self._pfp__init(stream)
@@ -125,15 +149,22 @@ def __init__(self, stream=None, metadata_processor=None, do_init=True):
     def _pfp__init(self, stream):
         self._pfp__interp._handle_node(decls, ctxt=self, stream=stream)
 
+    cls_members = {
+        "__init__": __init__,
+        "_pfp__init": _pfp__init,
+        "_pfp__node": node,
+        "_pfp__interp": interp,
+    }
+
+    for k, v in six.iteritems(overrides or {}):
+        if k in cls_members:
+            cls_members[k + "_orig"] = cls_members[k]
+        cls_members[k] = v
+
     new_class = type(
         typedef_name,
         (cls,),
-        {
-            "__init__": __init__,
-            "_pfp__init": _pfp__init,
-            "_pfp__node": node,
-            "_pfp__interp": interp,
-        },
+        cls_members,
     )
     return new_class
 
diff --git a/requirements.txt b/requirements.txt
index 819a4aa..e097781 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
-py010parser>=0.1.15
+py010parser>=0.1.17
 six>=1.10.0,<2.0.0
-intervaltree>=3.0.2,<4.0.0
\ No newline at end of file
+intervaltree>=3.0.2,<4.0.0
diff --git a/tests/test_struct_union.py b/tests/test_struct_union.py
index bbdf8ab..d0197e6 100644
--- a/tests/test_struct_union.py
+++ b/tests/test_struct_union.py
@@ -94,7 +94,7 @@ def test_struct_vit9696_5(self):
                 LittleEndian();
                 ME s;
             """,
-            debug=True,
+            debug=False,
         )
         assert dom.s.magic == "\x00\x01\x02\x03"
         assert dom.s.filesize == 0x03020100
@@ -239,6 +239,30 @@ def test_struct_with_parameters3(self):
         self.assertEqual(dom.l.c[1], 2)
         self.assertEqual(dom.l.c[2], 3)
 
+    def test_typedefd_struct_with_parameters(self):
+        dom = self._test_parse_build(
+            "\x01\x02\x03\x04\x01\x02\x03",
+            """
+                struct TEST_STRUCT(int arraySize, int arraySize2)
+                {
+                    uchar b[arraySize];
+                    uchar c[arraySize2];
+                };
+                local int bytes = 4;
+                typedef struct TEST_STRUCT NEW_STRUCT;
+                NEW_STRUCT l(bytes, 3);
+            """,
+        )
+        self.assertEqual(len(dom.l.b), 4)
+        self.assertEqual(dom.l.b[0], 1)
+        self.assertEqual(dom.l.b[1], 2)
+        self.assertEqual(dom.l.b[2], 3)
+        self.assertEqual(dom.l.b[3], 4)
+        self.assertEqual(len(dom.l.c), 3)
+        self.assertEqual(dom.l.c[0], 1)
+        self.assertEqual(dom.l.c[1], 2)
+        self.assertEqual(dom.l.c[2], 3)
+
     def test_struct_decl_with_struct_keyword(self):
         dom = self._test_parse_build(
             "ABCD",