diff --git a/tox.ini b/tox.ini
index b023ea312b..f42710b7be 100644
--- a/tox.ini
+++ b/tox.ini
@@ -20,6 +20,7 @@ passenv =
     # Pass HOME to the test environment to avoid the missing HOME env
     # variable error. See issue: #20424
     HOME
+    TEST_FLAGS
 
 
 [flake8]