diff --git a/rllib/agents/sac/sac_tf_model.py b/rllib/agents/sac/sac_tf_model.py
index b457f1e94..546de04ab 100644
--- a/rllib/agents/sac/sac_tf_model.py
+++ b/rllib/agents/sac/sac_tf_model.py
@@ -170,7 +170,7 @@ class SACTFModel(TFModelV2):
                 self.concat_obs_and_actions = True
             else:
                 if isinstance(orig_space, gym.spaces.Tuple):
-                    spaces = orig_space.spaces
+                    spaces = list(orig_space.spaces)
                 elif isinstance(orig_space, gym.spaces.Dict):
                     spaces = list(orig_space.spaces.values())
                 else:
diff --git a/rllib/agents/sac/sac_torch_model.py b/rllib/agents/sac/sac_torch_model.py
index 1288d20da..b1ba49199 100644
--- a/rllib/agents/sac/sac_torch_model.py
+++ b/rllib/agents/sac/sac_torch_model.py
@@ -176,7 +176,7 @@ class SACTorchModel(TorchModelV2, nn.Module):
                 self.concat_obs_and_actions = True
             else:
                 if isinstance(orig_space, gym.spaces.Tuple):
-                    spaces = orig_space.spaces
+                    spaces = list(orig_space.spaces)
                 elif isinstance(orig_space, gym.spaces.Dict):
                     spaces = list(orig_space.spaces.values())
                 else:
diff --git a/rllib/agents/sac/tests/test_sac.py b/rllib/agents/sac/tests/test_sac.py
index 33e816ee9..77923db83 100644
--- a/rllib/agents/sac/tests/test_sac.py
+++ b/rllib/agents/sac/tests/test_sac.py
@@ -100,9 +100,8 @@ class TestSAC(unittest.TestCase):
                 print("Env={}".format(env))
                 if env == RandomEnv:
                     config["env_config"] = {
-                        "observation_space": Tuple(
-                            [simple_space,
-                             Discrete(2), image_space]),
+                        "observation_space": Tuple((simple_space, Discrete(2),
+                                                    image_space)),
                         "action_space": Box(-1.0, 1.0, shape=(1, )),
                     }
                 else: