diff --git a/src/pretix/testutils/mock.py b/src/pretix/testutils/mock.py
index 70768c11d..30b9046ab 100644
--- a/src/pretix/testutils/mock.py
+++ b/src/pretix/testutils/mock.py
@@ -19,6 +19,7 @@
 # You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
 # <https://www.gnu.org/licenses/>.
 #
+import os
 from contextlib import contextmanager
 
 import fakeredis