diff --git a/libs/standard-tests/langchain_standard_tests/unit_tests/chat_models.py b/libs/standard-tests/langchain_standard_tests/unit_tests/chat_models.py
index 6ad014bab3f..1d7444ee4ba 100644
--- a/libs/standard-tests/langchain_standard_tests/unit_tests/chat_models.py
+++ b/libs/standard-tests/langchain_standard_tests/unit_tests/chat_models.py
@@ -5,13 +5,12 @@ from typing import Any, List, Literal, Optional, Tuple, Type
 from unittest import mock
 
 import pytest
-from syrupy import SnapshotAssertion
-
 from langchain_core.language_models import BaseChatModel
 from langchain_core.load import dumpd, load
 from langchain_core.pydantic_v1 import BaseModel, Field, SecretStr
 from langchain_core.runnables import RunnableBinding
 from langchain_core.tools import tool
+from syrupy import SnapshotAssertion
 
 from langchain_standard_tests.base import BaseStandardTests
 from langchain_standard_tests.utils.pydantic import PYDANTIC_MAJOR_VERSION
@@ -231,6 +230,8 @@ class ChatModelUnitTests(ChatModelTests):
     def test_serdes(self, model: BaseChatModel, snapshot: SnapshotAssertion) -> None:
         if not self.chat_model_class.is_lc_serializable():
             return
-        ser = dumpd(model)
-        assert ser == snapshot(name="serialized")
-        assert model.dict() == load(dumpd(model)).dict()
+        env_params, model_params, expected_attrs = self.init_from_env_params
+        with mock.patch.dict(os.environ, env_params):
+            ser = dumpd(model)
+            assert ser == snapshot(name="serialized")
+            assert model.dict() == load(dumpd(model)).dict()