diff --git a/lmdeploy/model.py b/lmdeploy/model.py
index 8920c4308e..b699fe4242 100644
--- a/lmdeploy/model.py
+++ b/lmdeploy/model.py
@@ -988,7 +988,7 @@ def messages2prompt(self,
                        system=self.system)
         ret = ''
         tool_prompt = ''
-        if tools is not None:
+        if tools is not None and len(tools) > 0:
             for tool in tools:
                 tool_prompt += self.separator
                 tool_prompt += f'{{"type": "function", "function": {json.dumps(tool, ensure_ascii=False)}}}'
diff --git a/tests/test_lmdeploy/test_model.py b/tests/test_lmdeploy/test_model.py
index c4faf77761..ae21053308 100644
--- a/tests/test_lmdeploy/test_model.py
+++ b/tests/test_lmdeploy/test_model.py
@@ -291,6 +291,28 @@ def test_qwen2d5():
     assert model.get_prompt(prompt, sequence_start=False) == prompt
 
     model = MODELS.get('qwen2d5')(capability='chat')
+
+    # No tool call
+    messages = [
+        dict(role='user',
+             content='What\'s the temperature in San Francisco now?')
+    ]
+    no_tool_prompt = ('<|im_start|>system\nYou are Qwen, created by Alibaba '
+                      'Cloud. You are a helpful '
+                      "assistant.<|im_end|>\n<|im_start|>user\nWhat's the "
+                      'temperature in San Francisco '
+                      'now?<|im_end|>\n<|im_start|>assistant\n')
+    assert model.messages2prompt(messages) == no_tool_prompt
+    assert model.messages2prompt(messages, tools=[]) == no_tool_prompt
+
+    messages.append({'role': 'assistant', 'content': 'I don\'t know.'})
+    no_tool_prompt = ('<|im_start|>system\nYou are Qwen, created by Alibaba '
+                      'Cloud. You are a helpful '
+                      "assistant.<|im_end|>\n<|im_start|>user\nWhat's the "
+                      'temperature in San Francisco '
+                      "now?<|im_end|>\n<|im_start|>assistant\nI don't "
+                      'know.<|im_end|>\n<|im_start|>assistant\n')
+    assert model.messages2prompt(messages) == no_tool_prompt
     # Single tool call
     tools = [{
         'name': 'get_current_temperature',