diff --git a/docker/manager.py b/docker/manager.py
index 7d7f60a..c99e9f7 100644
--- a/docker/manager.py
+++ b/docker/manager.py
@@ -185,7 +185,7 @@ def list_files(self, path):
 
         # `grep -v /$` matches everything that doesn't end with a
         # trailing slash, i.e. only files since `ls -p` is used:
-        result = self.run('ls -p | grep --color=never -v /$', path)
+        result = self.run('ls -p | grep -v /$', path)
 
         if not result.succeeded:
             if errors.FILE_NOT_FOUND_PREDICATE in result.err:
diff --git a/tests/test_manager.py b/tests/test_manager.py
index bed8593..858a2e6 100644
--- a/tests/test_manager.py
+++ b/tests/test_manager.py
@@ -82,9 +82,9 @@ def test_quotation_mark_handling(self, mock_run):
     @mock.patch('re.search', lambda *x: None)
     def test_env_variables(self, mock_run):
         docker = Docker(env_variables={'CI': 1, 'FRIGG': 1})
-        docker.run('ls')
+        docker.run('ls', login=True)
         mock_run.assert_called_once_with(
-            'docker exec -i -t {} bash --login -c \'cd ~/ && CI=1 FRIGG=1 ls\''.format(
+            'docker exec -i {0} bash --login -c \'cd ~/ && CI=1 FRIGG=1 ls\''.format(
                 docker.container_name
             ),
             ''