diff --git a/environment.yml b/environment.yml
index 609a850..f485394 100644
--- a/environment.yml
+++ b/environment.yml
@@ -3,7 +3,7 @@ channels:
   - conda-forge
   - defaults
 dependencies:
-  - atari_py=0.2 # used only in chapter 18
+  - atari_py=0.2.6 # used only in chapter 18
   - box2d-py=2.3 # used only in chapter 18
   - ftfy=5.8 # used only in chapter 16 by the transformers library
   - graphviz # used only in chapter 6 for dot files