diff --git a/python/cucim/pyproject.toml b/python/cucim/pyproject.toml
index afd1e05d..09ba8d15 100644
--- a/python/cucim/pyproject.toml
+++ b/python/cucim/pyproject.toml
@@ -168,6 +168,8 @@ fix = true
 # see: https://docs.astral.sh/ruff/rules/
 select = ["E", "F", "W", "I", "UP"]
 ignore = [
+    # (pycodestyle) Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
+    "E721",
     # (pyupgrade) Use `X | Y` in `isinstance` call instead of `(X, Y)`
     "UP038",
 ]