diff --git a/vllm/entrypoints/chat_utils.py b/vllm/entrypoints/chat_utils.py
index 0b662f1a7ec3..2e19ebcdd61f 100644
--- a/vllm/entrypoints/chat_utils.py
+++ b/vllm/entrypoints/chat_utils.py
@@ -1095,7 +1095,11 @@ def _parse_chat_message_content(
         if role == 'assistant':
             parsed_msg = _AssistantParser(message)
 
-            if "tool_calls" in parsed_msg:
+            # The 'tool_calls' is not None check ensures compatibility.
+            # It's needed only if downstream code doesn't strictly
+            # follow the OpenAI spec.
+            if ("tool_calls" in parsed_msg
+                and parsed_msg["tool_calls"] is not None):
                 result_msg["tool_calls"] = list(parsed_msg["tool_calls"])
         elif role == "tool":
             parsed_msg = _ToolParser(message)