diff --git a/formate.toml b/formate.toml
index 08a2c03..72f181d 100644
--- a/formate.toml
+++ b/formate.toml
@@ -31,6 +31,7 @@ known_third_party = [
     "coincidence",
     "coverage",
     "coverage_pyver_pragma",
+    "defusedxml",
     "docutils",
     "domdf_python_tools",
     "importlib_metadata",