--- a/ipc/ipdl/ipdl/__init__.py
+++ b/ipc/ipdl/ipdl/__init__.py
@@ -4,35 +4,39 @@
 
 __all__ = [ 'gencxx', 'genipdl', 'parse', 'typecheck', 'writeifmodified' ]
 
 import os, sys
 from cStringIO import StringIO
 
 from ipdl.cgen import IPDLCodeGen
 from ipdl.lower import LowerToCxx, msgenums
-from ipdl.parser import Parser
+from ipdl.parser import Parser, ParseError
 from ipdl.type import TypeCheck
 
 from ipdl.cxx.cgen import CxxCodeGen
 
 
 def parse(specstring, filename='/stdin', includedirs=[ ], errout=sys.stderr):
     '''Return an IPDL AST if parsing was successful.  Print errors to |errout|
     if it is not.'''
     # The file type and name are later enforced by the type checker.
     # This is just a hint to the parser.
     prefix, ext = os.path.splitext(filename)
     name = os.path.basename(prefix)
     if ext == '.ipdlh':
         type = 'header'
     else:
         type = 'protocol'
-    return Parser(type, name).parse(specstring, os.path.abspath(filename), includedirs, errout)
 
+    try:
+        return Parser(type, name).parse(specstring, os.path.abspath(filename), includedirs, errout)
+    except ParseError as p:
+        print >>errout, p
+        return None
 
 def typecheck(ast, errout=sys.stderr):
     '''Return True iff |ast| is well typed.  Print errors to |errout| if
     it is not.'''
     return TypeCheck().check(ast, errout)
 
 
 def gencxx(ipdlfilename, ast, outheadersdir, outcppdir):

--- a/ipc/ipdl/ipdl/parser.py
+++ b/ipc/ipdl/ipdl/parser.py
@@ -73,21 +73,19 @@ class Parser:
 
         Parser.parsed[filename] = self
         Parser.parseStack.append(Parser.current)
         Parser.current = self
 
         try:
             ast = self.parser.parse(input=input, lexer=self.lexer,
                                     debug=self.debug)
-        except ParseError, p:
-            print >>errout, p
-            return None
+        finally:
+            Parser.current = Parser.parseStack.pop()
 
-        Parser.current = Parser.parseStack.pop()
         return ast
 
     def resolveIncludePath(self, filepath):
         '''Return the absolute path from which the possibly partial
 |filepath| should be read, or |None| if |filepath| cannot be located.'''
         for incdir in self.includedirs +[ '' ]:
             realpath = os.path.join(incdir, filepath)
             if os.path.isfile(realpath):