diff --git a/baselines/common/cmd_util.py b/baselines/common/cmd_util.py
index 586480c..86f6248 100644
--- a/baselines/common/cmd_util.py
+++ b/baselines/common/cmd_util.py
@@ -81,8 +81,7 @@ def make_env(env_id, env_type, mpi_rank=0, subrank=0, seed=None, reward_scale=1.
         env = gym.make(env_id, **env_kwargs)
 
     if flatten_dict_observations and isinstance(env.observation_space, gym.spaces.Dict):
-        keys = env.observation_space.spaces.keys()
-        env = gym.wrappers.FlattenDictWrapper(env, dict_keys=list(keys))
+        env = gym.wrappers.FlattenObservation(env)
 
     env.seed(seed + subrank if seed is not None else None)
     env = Monitor(env,
diff --git a/setup.py b/setup.py
index e48f269..9f1bae0 100644
--- a/setup.py
+++ b/setup.py
@@ -31,7 +31,7 @@ setup(name='baselines',
       packages=[package for package in find_packages()
                 if package.startswith('baselines')],
       install_requires=[
-          'gym>=0.10.0, <1.0.0',
+          'gym>=0.15.4, <1.0.0',
           'scipy',
           'tqdm',
           'joblib',