diff --git a/libs/partners/mistralai/langchain_mistralai/chat_models.py b/libs/partners/mistralai/langchain_mistralai/chat_models.py
index 7cdac2bcab3..6f3cac19904 100644
--- a/libs/partners/mistralai/langchain_mistralai/chat_models.py
+++ b/libs/partners/mistralai/langchain_mistralai/chat_models.py
@@ -274,7 +274,9 @@ def _convert_chunk_to_message_chunk(
             }
         else:
             usage_metadata = None
-        if _choice.get("finish_reason") is not None:
+        if _choice.get("finish_reason") is not None and isinstance(
+            chunk.get("model"), str
+        ):
             response_metadata["model_name"] = chunk.get("model")
         return AIMessageChunk(
             content=content,