diff --git a/pyproject.toml b/pyproject.toml
index 3e482142..5c607a17 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -26,7 +26,7 @@ classifiers = [
 dependencies = [
     "mujoco>=2.3.3, <3.0",
     "numpy>=1.21.0",
-    "gymnasium>=0.26",
+    "gymnasium==1.0.0a1",
     "PettingZoo>=1.23.0",
     "Jinja2>=3.0.3",
     "imageio"