diff --git a/python/langsmith/client.py b/python/langsmith/client.py
index 4f5e171bc..73519126a 100644
--- a/python/langsmith/client.py
+++ b/python/langsmith/client.py
@@ -290,10 +290,14 @@ def _get_tracing_sampling_rate() -> float | None:
 
 
 def _get_api_key(api_key: Optional[str]) -> Optional[str]:
-    api_key = api_key or os.getenv("LANGSMITH_API_KEY", os.getenv("LANGCHAIN_API_KEY"))
-    if api_key is None or not api_key.strip():
+    api_key_ = (
+        api_key
+        if api_key is not None
+        else os.getenv("LANGSMITH_API_KEY", os.getenv("LANGCHAIN_API_KEY"))
+    )
+    if api_key_ is None or not api_key_.strip():
         return None
-    return api_key.strip().strip('"').strip("'")
+    return api_key_.strip().strip('"').strip("'")
 
 
 def _get_api_url(api_url: Optional[str]) -> str:
@@ -452,7 +456,7 @@ def __init__(
         ) and os.getenv("LANGSMITH_RUNS_ENDPOINTS"):
             raise ls_utils.LangSmithUserError(
                 "You cannot provide both LANGSMITH_ENDPOINT / LANGCHAIN_ENDPOINT "
-                "and LANGSMITH_ENDPOINTS."
+                "and LANGSMITH_RUNS_ENDPOINTS."
             )
 
         self.tracing_sample_rate = _get_tracing_sampling_rate()
diff --git a/python/tests/unit_tests/test_client.py b/python/tests/unit_tests/test_client.py
index efce9c394..019253137 100644
--- a/python/tests/unit_tests/test_client.py
+++ b/python/tests/unit_tests/test_client.py
@@ -150,6 +150,8 @@ def test_validate_multiple_urls(monkeypatch: pytest.MonkeyPatch) -> None:
         "https://api.smith.langsmith-endpoint_2.com": "456",
         "https://api.smith.langsmith-endpoint_3.com": "789",
     }
+    monkeypatch.delenv("LANGCHAIN_ENDPOINT")
+    monkeypatch.delenv("LANGSMITH_ENDPOINT", raising=False)
     monkeypatch.setenv("LANGSMITH_RUNS_ENDPOINTS", json.dumps(data))
     client = Client()
     assert client._write_api_urls == data