diff --git a/xarray/tests/test_cftime_offsets.py b/xarray/tests/test_cftime_offsets.py
index 1277b7d6c01..b06b6b4063a 100644
--- a/xarray/tests/test_cftime_offsets.py
+++ b/xarray/tests/test_cftime_offsets.py
@@ -1540,7 +1540,7 @@ def test_date_range_like_errors():
         date_range_like(da, "noleap")
 
 
-def as_timedelta_not_implemented_error():
+def test_as_timedelta_not_implemented_error():
     tick = Tick()
     with pytest.raises(NotImplementedError):
         tick.as_timedelta()