diff --git a/Parser/asdl.py b/Parser/asdl.py
index ce9d0d3..28a7138 100644
--- a/Parser/asdl.py
+++ b/Parser/asdl.py
@@ -20,7 +20,7 @@
     sys.stdout.write(string + "\n")
 
 
-class Token:
+class Token(object):
     # spark seems to dispatch in the parser based on a token's
     # type attribute
     def __init__(self, type, lineno):
@@ -221,20 +221,20 @@
     def p_field_2(self, info):
         " field ::= Id * Id "
         type, _, name = info
-        return Field(type, name, seq=1)
+        return Field(type, name, seq=True)
 
     def p_field_3(self, info):
         " field ::= Id ? Id "
         type, _, name = info
-        return Field(type, name, opt=1)
+        return Field(type, name, opt=True)
 
     def p_field_4(self, type_):
         " field ::= Id * "
-        return Field(type_[0], seq=1)
+        return Field(type_[0], seq=True)
 
     def p_field_5(self, type_):
         " field ::= Id ? "
-        return Field(type[0], opt=1)
+        return Field(type[0], opt=True)
 
 builtin_types = ("identifier", "string", "int", "bool", "object")
 
@@ -242,7 +242,7 @@
 # not sure if any of the methods are useful yet, but I'm adding them
 # piecemeal as they seem helpful
 
-class AST:
+class AST(object):
     pass # a marker class
 
 class Module(AST):
@@ -274,7 +274,7 @@
         return "Constructor(%s, %s)" % (self.name, self.fields)
 
 class Field(AST):
-    def __init__(self, type, name=None, seq=0, opt=0):
+    def __init__(self, type, name=None, seq=False, opt=False):
         self.type = type
         self.name = name
         self.seq = seq
@@ -282,9 +282,9 @@
 
     def __repr__(self):
         if self.seq:
-            extra = ", seq=1"
+            extra = ", seq=True"
         elif self.opt:
-            extra = ", opt=1"
+            extra = ", opt=True"
         else:
             extra = ""
         if self.name is None:
@@ -312,7 +312,7 @@
 
 class VisitorBase(object):
 
-    def __init__(self, skip=0):
+    def __init__(self, skip=False):
         self.cache = {}
         self.skip = skip
 
@@ -347,7 +347,7 @@
 class Check(VisitorBase):
 
     def __init__(self):
-        super(Check, self).__init__(skip=1)
+        super(Check, self).__init__(skip=True)
         self.cons = {}
         self.errors = 0
         self.types = {}
diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index af0b349..8ccb3ea 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -86,7 +86,7 @@
         self.file = file
         super(EmitVisitor, self).__init__()
 
-    def emit(self, s, depth, reflow=1):
+    def emit(self, s, depth, reflow=True):
         # XXX reflow long lines?
         if reflow:
             lines = reflow_lines(s, depth)
@@ -255,7 +255,7 @@
         ctype = get_c_type(type)
         self.emit_function(cons.name, ctype, args, attrs)
 
-    def emit_function(self, name, ctype, args, attrs, union=1):
+    def emit_function(self, name, ctype, args, attrs, union=True):
         args = args + attrs
         if args:
             argstr = ", ".join(["%s %s" % (atype, aname)
@@ -267,19 +267,19 @@
         for i in range(1, len(args)+1):
             margs += ", a%d" % i
         self.emit("#define %s(%s) _Py_%s(%s)" % (name, margs, name, margs), 0,
-                reflow = 0)
-        self.emit("%s _Py_%s(%s);" % (ctype, name, argstr), 0)
+                reflow=False)
+        self.emit("%s _Py_%s(%s);" % (ctype, name, argstr), False)
 
     def visitProduct(self, prod, name):
         self.emit_function(name, get_c_type(name),
-                           self.get_args(prod.fields), [], union=0)
+                           self.get_args(prod.fields), [], union=False)
 
 
 class FunctionVisitor(PrototypeVisitor):
     """Visitor to generate constructor functions for AST."""
 
-    def emit_function(self, name, ctype, args, attrs, union=1):
-        def emit(s, depth=0, reflow=1):
+    def emit_function(self, name, ctype, args, attrs, union=True):
+        def emit(s, depth=0, reflow=True):
             self.emit(s, depth, reflow)
         argstr = ", ".join(["%s %s" % (atype, aname)
                             for atype, aname, opt in args + attrs])
@@ -297,7 +297,7 @@
                 emit("PyErr_SetString(PyExc_ValueError,", 2)
                 msg = "field %s is required for %s" % (argname, name)
                 emit('                "%s");' % msg,
-                     2, reflow=0)
+                     2, reflow=False)
                 emit('return NULL;', 2)
                 emit('}', 1)
 
@@ -313,7 +313,7 @@
         emit("")
 
     def emit_body_union(self, name, args, attrs):
-        def emit(s, depth=0, reflow=1):
+        def emit(s, depth=0, reflow=True):
             self.emit(s, depth, reflow)
         emit("p->kind = %s_kind;" % name, 1)
         for argtype, argname, opt in args:
@@ -322,7 +322,7 @@
             emit("p->%s = %s;" % (argname, argname), 1)
 
     def emit_body_struct(self, name, args, attrs):
-        def emit(s, depth=0, reflow=1):
+        def emit(s, depth=0, reflow=True):
             self.emit(s, depth, reflow)
         for argtype, argname, opt in args:
             emit("p->%s = %s;" % (argname, argname), 1)