diff --git a/chatbot_ui/common.py b/chatbot_ui/common.py
index 19111668..5fd33c5f 100644
--- a/chatbot_ui/common.py
+++ b/chatbot_ui/common.py
@@ -1,5 +1,6 @@
 import json
 import logging
+import os
 import yaml
 
 logging.basicConfig(
diff --git a/chatbot_ui/run_stream.py b/chatbot_ui/run_stream.py
index 798a2d5e..76ca8742 100644
--- a/chatbot_ui/run_stream.py
+++ b/chatbot_ui/run_stream.py
@@ -83,7 +83,9 @@ def chat(query: Optional[str], conversation: Optional[List[Tuple[str, str]]], st
         if message.content:
             history[-1]["content"] = history[-1].get("content", "") + message.content
 
-        if history[-1]["role"] != "tool" and message.content:
+        # message.content is none for tool calls
+        # when "role = tool" content would contain api call response
+        if message.content and history[-1]["role"] != "tool":
             conversation[-1] = (
                 conversation[-1][0],
                 conversation[-1][1] + message.content,