diff --git a/pyproject.toml b/pyproject.toml
index 9c95105e..83b13da9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -52,6 +52,7 @@ tests = [
   "pytest-mock",
   "pytest-mpl",
   "pytest-httpserver",
+  "pytest-filter-subpackage",
   "hypothesis",
   "tox",
   "pydot",