diff --git a/libs/langchain/langchain/schema/runnable/base.py b/libs/langchain/langchain/schema/runnable/base.py
index d3e8d9e85d8..c727ba676c1 100644
--- a/libs/langchain/langchain/schema/runnable/base.py
+++ b/libs/langchain/langchain/schema/runnable/base.py
@@ -1575,15 +1575,15 @@ class RunnableBinding(Serializable, Runnable[Input, Output]):
         config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
         **kwargs: Optional[Any],
     ) -> List[Output]:
-        configs = cast(
-            List[RunnableConfig],
-            [self._merge_config(conf) for conf in config]
-            if isinstance(config, list)
-            else [
+        if isinstance(config, list):
+            configs = cast(
+                List[RunnableConfig], [self._merge_config(conf) for conf in config]
+            )
+        else:
+            configs = [
                 patch_config(self._merge_config(config), deep_copy_locals=True)
                 for _ in range(len(inputs))
-            ],
-        )
+            ]
         return self.bound.batch(inputs, configs, **{**self.kwargs, **kwargs})
 
     async def abatch(