diff --git a/core/lexer_gen_test.py b/core/lexer_gen_test.py
@@ -0,0 +1,48 @@
+#!/usr/bin/python -S
+"""
+lex_gen_test.py: Tests for lex_gen.py
+"""
+
+import unittest
+
+from osh import lex
+from core import lexer_gen  # module under test
+
+
+class LexerGenTest(unittest.TestCase):
+
+  def testTranslateRegex(self):
+    PAIRS = [
+        (r'a', r'a'),
+        (r'[a-z]', r'[a-z]'),
+        (r'[a-zA-Z.]+', r'[a-zA-Z.]+'),
+        (r'[a-zA-Z_][a-zA-Z0-9_]*\+?=', r'[a-zA-Z_][a-zA-Z0-9_]*\+?='),
+
+        (r'[."]*', r'[.\"]*'),
+        (r'\$', r'\$'),
+        (r'.*', r'.*'),
+
+        # Both of these accepted?
+        ('\0', r'\000'),
+        (r'\0', r'\000'),
+        (r'\\', r'\\'),
+        (r'[\\]', r'\\'),
+
+        (r'.', r'.'),
+        (r'[^a]', r'[^a]'),
+        (r'[^a-z]', r'[^a-z]'),
+        # . isn't special inside
+        (r'[a\.]', r'[a.]'),
+    ]
+    for py, expected in PAIRS:
+      #self.assertEqual(expected, lexer_gen.TranslateRegex(py))
+      print '---', py
+      actual = lexer_gen.TranslateRegex(py)
+      print repr(actual)
+      self.assertEqual(expected, actual)
+      print
+      print
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/native/fastlex.c b/native/fastlex.c
@@ -38,8 +38,10 @@ fastlex_MatchToken(PyObject *self, PyObject *args) {
                        &lex_mode, &line, &line_len, &start_pos)) {
    return NULL;
  }
+  /*
  debug("lex_mode %d, line_len %d, start_pos %d\n",
        lex_mode, line_len, start_pos);
+  */

  /*
  for (int i = 0; i < line_len; ++i) {
diff --git a/osh/lex_gen.py b/osh/lex_gen.py
diff --git a/osh/parse_lib.py b/osh/parse_lib.py
@@ -49,7 +49,6 @@ def MatchToken_Fast(lex_mode, line, start_pos):

 def _MakeMatcher():
  # NOTE: Could have an environment variable to control this for speed?
-
  return MatchToken_Slow(lex.LEXER_DEF)

  if fastlex: