diff --git a/pyproject.toml b/pyproject.toml
index 81c1f74b..dd0542b0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -42,6 +42,7 @@ testing = [
     "cython<3",
     "PettingZoo>=1.23.0",
     "Jinja2>=3.0.3",
+    "disutils"
 ]
 mujoco_py = ["mujoco_py<2.2,>=2.1", "cython<3"]