diff --git a/src/aws_durable_execution_sdk_python_testing/executor.py b/src/aws_durable_execution_sdk_python_testing/executor.py
index d2ff0c6..3df4ed8 100644
--- a/src/aws_durable_execution_sdk_python_testing/executor.py
+++ b/src/aws_durable_execution_sdk_python_testing/executor.py
@@ -360,7 +360,7 @@ def get_execution_state(
         execution = self.get_execution(execution_arn)
 
         # TODO: Validate checkpoint token if provided
-        if checkpoint_token and checkpoint_token not in execution.used_tokens:
+        if checkpoint_token and checkpoint_token in execution.used_tokens:
             msg: str = f"Invalid checkpoint token: {checkpoint_token}"
             raise InvalidParameterValueException(msg)
 
@@ -469,7 +469,7 @@ def checkpoint_execution(
         execution = self.get_execution(execution_arn)
 
         # Validate checkpoint token
-        if checkpoint_token not in execution.used_tokens:
+        if checkpoint_token in execution.used_tokens:
             msg: str = f"Invalid checkpoint token: {checkpoint_token}"
             raise InvalidParameterValueException(msg)
 
diff --git a/tests/executor_test.py b/tests/executor_test.py
index 78a067e..a53797a 100644
--- a/tests/executor_test.py
+++ b/tests/executor_test.py
@@ -1916,7 +1916,7 @@ def test_get_execution_state(executor, mock_store):
 
     mock_store.load.return_value = mock_execution
 
-    result = executor.get_execution_state("test-arn", checkpoint_token="token1")  # noqa: S106
+    result = executor.get_execution_state("test-arn", checkpoint_token="token3")  # noqa: S106
 
     assert len(result.operations) == 2
     assert result.next_marker is None
@@ -1932,7 +1932,7 @@ def test_get_execution_state_invalid_token(executor, mock_store):
     with pytest.raises(
         InvalidParameterValueException, match="Invalid checkpoint token"
     ):
-        executor.get_execution_state("test-arn", checkpoint_token="invalid-token")  # noqa: S106
+        executor.get_execution_state("test-arn", checkpoint_token="token1")  # noqa: S106
 
 
 def test_get_execution_history(executor, mock_store):
@@ -1954,7 +1954,7 @@ def test_checkpoint_execution(executor, mock_store):
     mock_execution.get_new_checkpoint_token.return_value = "new-token"
     mock_store.load.return_value = mock_execution
 
-    result = executor.checkpoint_execution("test-arn", "token1")
+    result = executor.checkpoint_execution("test-arn", "new-token")
 
     assert result.checkpoint_token == "new-token"  # noqa: S105
     assert result.new_execution_state is None
@@ -1971,7 +1971,7 @@ def test_checkpoint_execution_invalid_token(executor, mock_store):
     with pytest.raises(
         InvalidParameterValueException, match="Invalid checkpoint token"
     ):
-        executor.checkpoint_execution("test-arn", "invalid-token")
+        executor.checkpoint_execution("test-arn", "token1")
 
 
 # Callback method tests