diff --git a/tests/test-check-pyflakes.t b/tests/test-check-pyflakes.t
--- a/tests/test-check-pyflakes.t
+++ b/tests/test-check-pyflakes.t
@@ -17,6 +17,7 @@
   > -X hgext/fsmonitor/pywatchman \
   > -X mercurial/pycompat.py -X contrib/python-zstandard \
   > -X mercurial/thirdparty/cbor \
+  > -X mercurial/thirdparty/concurrent \
   > -X mercurial/thirdparty/zope \
   > 2>/dev/null \
   > | xargs pyflakes 2>/dev/null | "$TESTDIR/filterpyflakes.py"