diff --git a/tools/test-backend b/tools/test-backend
index f95970906f..f820943f03 100755
--- a/tools/test-backend
+++ b/tools/test-backend
@@ -123,6 +123,7 @@ not_yet_fully_covered = {path for target in [
     'zerver/tornado/websocket_client.py',
     # Data import files; relatively low priority
     'zerver/data_import/hipchat*.py',
+    'zerver/data_import/mattermost.py',
     'zerver/data_import/sequencer.py',
     'zerver/data_import/slack.py',
     'zerver/data_import/gitter.py',