diff --git a/stable_baselines3/common/buffers.py b/stable_baselines3/common/buffers.py
index 4d191fc..8e02b74 100644
--- a/stable_baselines3/common/buffers.py
+++ b/stable_baselines3/common/buffers.py
@@ -132,8 +132,8 @@ class BaseBuffer(ABC):
         :return:
         """
         if copy:
-            return th.tensor(array).to(self.device, non_blocking=True)
-        return th.as_tensor(array).to(self.device, non_blocking=True)
+            return th.tensor(array).to(self.device)
+        return th.as_tensor(array).to(self.device)
 
     @staticmethod
     def _normalize_obs(
diff --git a/stable_baselines3/common/utils.py b/stable_baselines3/common/utils.py
index b7c4cb9..1a3f871 100644
--- a/stable_baselines3/common/utils.py
+++ b/stable_baselines3/common/utils.py
@@ -461,9 +461,9 @@ def obs_as_tensor(
     :return: PyTorch tensor of the observation on a desired device.
     """
     if isinstance(obs, np.ndarray):
-        return th.as_tensor(obs).to(device, non_blocking=True)
+        return th.as_tensor(obs).to(device)
     elif isinstance(obs, dict):
-        return {key: th.as_tensor(_obs).to(device, non_blocking=True) for (key, _obs) in obs.items()}
+        return {key: th.as_tensor(_obs).to(device) for (key, _obs) in obs.items()}
     else:
         raise Exception(f"Unrecognized type of observation {type(obs)}")