diff --git a/pkgs/development/python-modules/gym/default.nix b/pkgs/development/python-modules/gym/default.nix
index d90ded1fb5f..52171470c27 100644
--- a/pkgs/development/python-modules/gym/default.nix
+++ b/pkgs/development/python-modules/gym/default.nix
@@ -5,11 +5,11 @@
 
 buildPythonPackage rec {
   pname = "gym";
-  version = "0.15.4";
+  version = "0.15.3";
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "3b930cbe1c76bbd30455b5e82ba723dea94159a5f988e927f443324bf7cc7ddd";
+    sha256 = "18381e13bbd1e2f206a1b88a2af4fb87affd7d06ee7955a6e5e6a79478a9adfc";
   };
 
   postPatch = ''