diff --git a/setup.py b/setup.py
index 2eda2828e..03c5b7055 100644
--- a/setup.py
+++ b/setup.py
@@ -162,7 +162,7 @@ def build_extension(self, ext):
         ext_modules=[setuptools.Extension("nle", sources=[])],
         cmdclass={"build_ext": CMakeBuild},
         setup_requires=["pybind11>=2.2"],
-        install_requires=["pybind11>=2.2", "numpy>=1.16", "gym>=0.15,<=0.23"],
+        install_requires=["pybind11>=2.2", "numpy>=1.16", "gym>=0.15,<=0.23,!=0.20"],
         extras_require=extras_deps,
         python_requires=">=3.5",
         classifiers=[