diff --git a/unit1/unit1.ipynb b/unit1/unit1.ipynb
index 173cc92..5776bb9 100644
--- a/unit1/unit1.ipynb
+++ b/unit1/unit1.ipynb
@@ -253,7 +253,7 @@
         "!pip install gym[box2d]\n",
         "!pip install stable-baselines3[extra]\n",
         "!pip install huggingface_sb3\n",
-        "!pip install pyglet\n",
+        "!pip install pyglet==1.5.1\n",
         "!pip install ale-py==0.7.4 # To overcome an issue with gym (https://github.com/DLR-RM/stable-baselines3/issues/875)\n",
         "\n",
         "!pip install pickle5"