diff --git a/libs/langchain/tests/unit_tests/schema/runnable/test_runnable.py b/libs/langchain/tests/unit_tests/schema/runnable/test_runnable.py
index 849031f875e..412fa8e1e7f 100644
--- a/libs/langchain/tests/unit_tests/schema/runnable/test_runnable.py
+++ b/libs/langchain/tests/unit_tests/schema/runnable/test_runnable.py
@@ -124,8 +124,8 @@ async def test_with_config(mocker: MockerFixture) -> None:
     ]
     spy.reset_mock()
 
-    fake_1 = RunnablePassthrough()
-    fake_2 = RunnablePassthrough()
+    fake_1: Runnable = RunnablePassthrough()
+    fake_2: Runnable = RunnablePassthrough()
     spy_seq_step = mocker.spy(fake_1.__class__, "invoke")
 
     sequence = fake_1.with_config(tags=["a-tag"]) | fake_2.with_config(