diff --git a/src/smolagents/models.py b/src/smolagents/models.py
index 11be825..172757e 100644
--- a/src/smolagents/models.py
+++ b/src/smolagents/models.py
@@ -132,8 +132,9 @@ def parse_json_if_needed(arguments: Union[str, dict]) -> Union[str, dict]:
 
 
 def parse_tool_args_if_needed(message: ChatMessage) -> ChatMessage:
-    for tool_call in message.tool_calls:
-        tool_call.function.arguments = parse_json_if_needed(tool_call.function.arguments)
+    if message.tool_calls is not None:
+        for tool_call in message.tool_calls:
+            tool_call.function.arguments = parse_json_if_needed(tool_call.function.arguments)
     return message
 
 
diff --git a/tests/test_models.py b/tests/test_models.py
index ea70983..8c83a9f 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -107,6 +107,11 @@ class ModelTests(unittest.TestCase):
         output = model(messages, stop_sequences=["great"]).content
         assert output == "Hello! How can"
 
+    def test_parse_tool_args_if_needed(self):
+        original_message = ChatMessage(role="user", content=[{"type": "text", "text": "Hello!"}])
+        parsed_message = models.parse_tool_args_if_needed(original_message)
+        assert parsed_message == original_message
+
     def test_parse_json_if_needed(self):
         args = "abc"
         parsed_args = parse_json_if_needed(args)