diff --git a/git_cl.py b/git_cl.py
index c03d6103d7..6658a2fa05 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -2517,10 +2517,14 @@ class _GerritChangelistImpl(_ChangelistCodereviewBase):
     # https://gerrit-review.googlesource.com/Documentation/user-upload.html
     refspec_opts = []
     if options.title:
+      if not re.match(r'^[\w ]+$', options.title):
+        options.title = re.sub(r'[^\w ]', '', options.title)
+        print('WARNING: Patchset title may only contain alphanumeric chars '
+              'and spaces. Cleaned up title:\n%s' % options.title)
+        if not options.force:
+          ask_for_data('Press enter to continue, Ctrl+C to abort')
       # Per doc, spaces must be converted to underscores, and Gerrit will do the
       # reverse on its side.
-      if '_' in options.title:
-        print('WARNING: underscores in title will be converted to spaces.')
       refspec_opts.append('m=' + options.title.replace(' ', '_'))
 
     if options.send_mail:
diff --git a/tests/git_cl_test.py b/tests/git_cl_test.py
index a8c4944f64..378525a005 100755
--- a/tests/git_cl_test.py
+++ b/tests/git_cl_test.py
@@ -974,13 +974,18 @@ class TestGitCl(TestCase):
         squash=False,
         squash_mode='override_nosquash')
 
-  def test_gerrit_patch_title(self):
+  def test_gerrit_patch_bad_chars(self):
+    self.mock(git_cl.sys, 'stdout', StringIO.StringIO())
     self._run_gerrit_upload_test(
-        ['-t', 'Don\'t put under_scores as they become spaces'],
+        ['-f', '-t', 'Don\'t put bad cha,.rs'],
         'desc\n\nBUG=\n\nChange-Id: I123456789',
         squash=False,
         squash_mode='override_nosquash',
-        ref_suffix='%m=Don\'t_put_under_scores_as_they_become_spaces')
+        ref_suffix='%m=Dont_put_bad_chars')
+    self.assertIn(
+        'WARNING: Patchset title may only contain alphanumeric chars '
+        'and spaces. Cleaned up title:\nDont put bad chars\n',
+        git_cl.sys.stdout.getvalue())
 
   def test_gerrit_reviewers_cmd_line(self):
     self._run_gerrit_upload_test(