diff --git a/libs/partners/ollama/langchain_ollama/chat_models.py b/libs/partners/ollama/langchain_ollama/chat_models.py
index 84742c7aa78..a9a6210f68f 100644
--- a/libs/partners/ollama/langchain_ollama/chat_models.py
+++ b/libs/partners/ollama/langchain_ollama/chat_models.py
@@ -165,7 +165,7 @@ def _parse_arguments_from_tool_call(
 
 def _get_tool_calls_from_response(
     response: Mapping[str, Any],
-    model_name: Optional[str] = None,
+    model_name: str = "",
 ) -> list[ToolCall]:
     """Get tool calls from ollama response.
     
@@ -1560,3 +1560,4 @@ class ChatOllama(BaseChatModel):
 
 
 
+