diff --git a/lib/crypto/tests.py b/lib/crypto/tests.py
index bb9934d46a..b33da4808d 100644
--- a/lib/crypto/tests.py
+++ b/lib/crypto/tests.py
@@ -15,6 +15,25 @@ from files.utils import SafeUnzip
 from lib.crypto import packaged
 from lib.crypto.receipt import crack, sign, SigningError
 from mkt.webapps.models import Webapp
+from versions.models import Version
+
+
+def mock_sign(version_id, reviewer=False):
+    """
+    This is a mock for using in tests, where we really don't want to be
+    actually signing the apps. This just copies the file over and returns
+    the path. It doesn't have much error checking.
+    """
+    version = Version.objects.get(pk=version_id)
+    file_obj = version.all_files[0]
+    path = (file_obj.signed_reviewer_file_path if reviewer else
+            file_obj.signed_file_path)
+    try:
+        os.makedirs(os.path.dirname(path))
+    except OSError:
+        pass
+    shutil.copyfile(file_obj.file_path, path)
+    return path
 
 
 @mock.patch('lib.metrics.urllib2.urlopen')
diff --git a/mkt/downloads/tests/test_views.py b/mkt/downloads/tests/test_views.py
index f48aa4384d..e9481a7b0d 100644
--- a/mkt/downloads/tests/test_views.py
+++ b/mkt/downloads/tests/test_views.py
@@ -5,6 +5,8 @@ from django.conf import settings
 
 import amo
 from amo.urlresolvers import reverse
+from lib.crypto import packaged
+from lib.crypto.tests import mock_sign
 from mkt.submit.tests.test_views import BasePackagedAppTest
 from mkt.webapps.models import Webapp
 
@@ -18,6 +20,7 @@ class TestDownload(BasePackagedAppTest):
         super(TestDownload, self).setup_files()
         self.url = reverse('downloads.file', args=[self.file.pk])
 
+    @mock.patch.object(packaged, 'sign', mock_sign)
     def test_download(self):
         res = self.client.get(self.url)
         eq_(res.status_code, 200)
@@ -27,11 +30,13 @@ class TestDownload(BasePackagedAppTest):
         self.app.update(status=amo.STATUS_DISABLED)
         eq_(self.client.get(self.url).status_code, 404)
 
+    @mock.patch.object(packaged, 'sign', mock_sign)
     def test_disabled_but_owner(self):
         self.client.login(username='steamcube@mozilla.com',
                           password='password')
         eq_(self.client.get(self.url).status_code, 200)
 
+    @mock.patch.object(packaged, 'sign', mock_sign)
     def test_disabled_but_admin(self):
         self.client.login(username='admin@mozilla.com',
                           password='password')
diff --git a/mkt/reviewers/tests/test_views.py b/mkt/reviewers/tests/test_views.py
index 3b93edf490..8df9d9121a 100644
--- a/mkt/reviewers/tests/test_views.py
+++ b/mkt/reviewers/tests/test_views.py
@@ -27,6 +27,8 @@ from devhub.models import ActivityLog, AppLog
 from editors.models import (CannedResponse, EscalationQueue, RereviewQueue,
                             ReviewerScore)
 from files.models import File
+from lib.crypto import packaged
+from lib.crypto.tests import mock_sign
 import mkt.constants.reviewers as rvw
 from mkt.reviewers.models import ThemeLock
 from mkt.submit.tests.test_views import BasePackagedAppTest
@@ -1824,6 +1826,7 @@ class TestGetSigned(BasePackagedAppTest, amo.tests.TestCase):
         self.client.login(username='regular@mozilla.com', password='password')
         eq_(self.client.get(self.url).status_code, 403)
 
+    @mock.patch.object(packaged, 'sign', mock_sign)
     def test_reviewer(self):
         self.setup_files()
         res = self.client.get(self.url)
diff --git a/mkt/webapps/tests/test_models.py b/mkt/webapps/tests/test_models.py
index 080508c4b4..46f76c6547 100644
--- a/mkt/webapps/tests/test_models.py
+++ b/mkt/webapps/tests/test_models.py
@@ -18,6 +18,8 @@ from amo.tests import (app_factory, ESTestCase, TestCase, version_factory,
 from constants.applications import DEVICE_TYPES
 from editors.models import RereviewQueue
 from files.models import File
+from lib.crypto import packaged
+from lib.crypto.tests import mock_sign
 from market.models import Price
 from users.models import UserProfile
 from versions.models import Version
@@ -426,6 +428,7 @@ class TestPackagedManifest(BasePackagedAppTest):
         eq_(data['icons'], manifest['icons'])
         eq_(data['locales'], manifest['locales'])
 
+    @mock.patch.object(packaged, 'sign', mock_sign)
     def test_package_path(self):
         webapp = self.post_addon()
         version = webapp.current_version