diff --git a/supersuit/utils/agent_indicator.py b/supersuit/utils/agent_indicator.py
index ba47d44..a37d763 100644
--- a/supersuit/utils/agent_indicator.py
+++ b/supersuit/utils/agent_indicator.py
@@ -12,7 +12,7 @@ def change_obs_space(space, num_indicators):
             pad_space = np.min(space.high) * np.ones(
                 (num_indicators,), dtype=space.dtype
             )
-            new_low = np.concatenate([space.low, pad_space * 0], axis=0)
+            new_low = np.concatenate([space.low, np.zeros_like(pad_space)], axis=0)
             new_high = np.concatenate([space.high, pad_space], axis=0)
             new_space = Box(low=new_low, high=new_high, dtype=space.dtype)
             return new_space
@@ -22,7 +22,7 @@ def change_obs_space(space, num_indicators):
             pad_space = np.min(space.high) * np.ones(
                 orig_low.shape[:2] + (num_indicators,), dtype=space.dtype
             )
-            new_low = np.concatenate([orig_low, pad_space * 0], axis=2)
+            new_low = np.concatenate([orig_low, np.zeros_like(pad_space)], axis=2)
             new_high = np.concatenate([orig_high, pad_space], axis=2)
             new_space = Box(low=new_low, high=new_high, dtype=space.dtype)
             return new_space
@@ -77,13 +77,22 @@ def change_observation(obs, space, indicator_data):
         if ndims == 1:
             old_len = len(obs)
             new_obs = np.pad(obs, (0, num_indicators))
-            new_obs[indicator_num + old_len] = np.max(space.high)
+            # if all spaces are finite, use the max, otherwise use 1.0 as agent indicator
+            if not np.isinf(space.high).any():
+                new_obs[indicator_num + old_len] = np.max(space.high)
+            else:
+                new_obs[indicator_num + old_len] = 1.0
+
             return new_obs
         elif ndims == 3 or ndims == 2:
             obs = obs if ndims == 3 else np.expand_dims(obs, 2)
             old_shaped3 = obs.shape[2]
             new_obs = np.pad(obs, [(0, 0), (0, 0), (0, num_indicators)])
-            new_obs[:, :, old_shaped3 + indicator_num] = np.min(space.high)
+            # if all spaces are finite, use the max, otherwise use 1.0 as agent indicator
+            if not np.isinf(space.high).any():
+                new_obs[:, :, old_shaped3 + indicator_num] = np.max(space.high)
+            else:
+                new_obs[:, :, old_shaped3 + indicator_num] = 1.0
             return new_obs
     elif isinstance(space, Discrete):
         return obs * num_indicators + indicator_num
diff --git a/test/aec_mock_test.py b/test/aec_mock_test.py
index 2dbce63..a425267 100644
--- a/test/aec_mock_test.py
+++ b/test/aec_mock_test.py
@@ -135,6 +135,30 @@ def test_agent_indicator():
     env.step(2)
 
 
+def test_agent_indicator_unbounded_box_space():
+    """
+    Test that if the observation space is unbounded e.g. space.high is inf,
+    then the agent indicator wrapper will not return inf as agent indicator.
+    """
+    let = ["a", "a", "b"]
+    base_obs = {f"{let[idx]}_{idx}": np.zeros([2, 3]) for idx in range(3)}
+    base_obs_space = {
+        f"{let[idx]}_{idx}": Box(low=0, high=np.inf, shape=[2, 3]) for idx in range(3)
+    }
+    base_act_spaces = {f"{let[idx]}_{idx}": Discrete(5) for idx in range(3)}
+
+    base_env = DummyEnv(base_obs, base_obs_space, base_act_spaces)
+    env = supersuit.agent_indicator_v0(base_env, type_only=True)
+    env.reset()
+    obs, _, _, _, _ = env.last()
+    assert obs.shape == (2, 3, 3)
+    assert env.observation_space("a_0").shape == (2, 3, 3)
+    # check agent indication is not inf
+    assert not np.isinf(obs).any()
+    # check agent indicator is 1.0
+    assert np.all(obs[:, :, 1] == 1.0)
+
+
 def test_reshape():
     base_env = DummyEnv(base_obs, base_obs_space, base_act_spaces)
     env = reshape_v0(base_env, (64, 3))