diff --git a/dulwich/tests/compat/test_porcelain.py b/dulwich/tests/compat/test_porcelain.py
index c5af2a0e..b05cad7d 100644
--- a/dulwich/tests/compat/test_porcelain.py
+++ b/dulwich/tests/compat/test_porcelain.py
@@ -1,97 +1,101 @@
 # test_porcelain .py -- Tests for dulwich.porcelain/CGit compatibility
 # Copyright (C) 2010 Google, Inc.
 #
 # Dulwich is dual-licensed under the Apache License, Version 2.0 and the GNU
 # General Public License as public by the Free Software Foundation; version 2.0
 # or (at your option) any later version. You can redistribute it and/or
 # modify it under the terms of either of these two licenses.
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
 # You should have received a copy of the licenses; if not, see
 # <http://www.gnu.org/licenses/> for a copy of the GNU General Public License
 # and <http://www.apache.org/licenses/LICENSE-2.0> for a copy of the Apache
 # License, Version 2.0.
 #
 
 """Compatibility tests for dulwich.porcelain."""
 
 import os
 import platform
 import sys
 from unittest import skipIf
 
 from dulwich import porcelain
 from dulwich.tests.utils import (
     build_commit_graph,
 )
 from dulwich.tests.compat.utils import (
     run_git_or_fail,
     CompatTestCase,
 )
 from dulwich.tests.test_porcelain import (
     PorcelainGpgTestCase,
 )
 
 
 @skipIf(platform.python_implementation() == "PyPy" or sys.platform == "win32", "gpgme not easily available or supported on Windows and PyPy")
 class TagCreateSignTestCase(PorcelainGpgTestCase, CompatTestCase):
     def setUp(self):
         super(TagCreateSignTestCase, self).setUp()
 
     def test_sign(self):
         # Test that dulwich signatures can be verified by CGit
         c1, c2, c3 = build_commit_graph(
             self.repo.object_store, [[1], [2, 1], [3, 1, 2]]
         )
         self.repo.refs[b"HEAD"] = c3.id
         cfg = self.repo.get_config()
         cfg.set(("user",), "signingKey", PorcelainGpgTestCase.DEFAULT_KEY_ID)
         self.import_default_key()
 
         porcelain.tag_create(
             self.repo.path,
             b"tryme",
             b"foo <foo@bar.com>",
             b"bar",
             annotated=True,
             sign=True,
         )
 
         run_git_or_fail(
             [
                 "--git-dir={}".format(self.repo.controldir()),
                 "tag",
                 "-v",
                 "tryme"
             ],
             env={'GNUPGHOME': os.environ['GNUPGHOME']},
         )
 
     def test_verify(self):
         # Test that CGit signatures can be verified by dulwich
         c1, c2, c3 = build_commit_graph(
             self.repo.object_store, [[1], [2, 1], [3, 1, 2]]
         )
         self.repo.refs[b"HEAD"] = c3.id
         self.import_default_key()
 
         run_git_or_fail(
             [
                 "--git-dir={}".format(self.repo.controldir()),
                 "tag",
                 "-u",
                 PorcelainGpgTestCase.DEFAULT_KEY_ID,
                 "-m",
                 "foo",
                 "verifyme",
             ],
-            env={'GNUPGHOME': os.environ['GNUPGHOME']},
+            env={
+                'GNUPGHOME': os.environ['GNUPGHOME'],
+                'GIT_COMMITTER_NAME': 'Joe Example',
+                'GIT_COMMITTER_EMAIL': 'joe@example.com',
+                },
         )
         tag = self.repo[b"refs/tags/verifyme"]
         self.assertNotEqual(tag.signature, None)
         tag.verify()