diff --git a/gymnasium/core.py b/gymnasium/core.py
index 8225e4905..9dfe63876 100644
--- a/gymnasium/core.py
+++ b/gymnasium/core.py
@@ -307,7 +307,9 @@ def __init__(self, env: Env[ObsType, ActType]):
             env: The environment to wrap
         """
         self.env = env
-        assert isinstance(env, Env)
+        assert isinstance(
+            env, Env
+        ), f"Expected env to be a `gymnasium.Env` but got {type(env)}"
 
         self._action_space: spaces.Space[WrapperActType] | None = None
         self._observation_space: spaces.Space[WrapperObsType] | None = None
diff --git a/gymnasium/vector/vector_env.py b/gymnasium/vector/vector_env.py
index 0956184f7..7a59a11a2 100644
--- a/gymnasium/vector/vector_env.py
+++ b/gymnasium/vector/vector_env.py
@@ -355,7 +355,9 @@ def __init__(self, env: VectorEnv):
             env: The environment to wrap
         """
         self.env = env
-        assert isinstance(env, VectorEnv)
+        assert isinstance(
+            env, VectorEnv
+        ), f"Expected env to be a `gymnasium.vector.VectorEnv` but got {type(env)}"
 
         self._observation_space: gym.Space | None = None
         self._action_space: gym.Space | None = None