diff --git a/chatbot_ui/app/run.py b/chatbot_ui/app/run.py
index c8fcccd1..b0d5acc6 100644
--- a/chatbot_ui/app/run.py
+++ b/chatbot_ui/app/run.py
@@ -143,10 +143,13 @@ def chat(query: Optional[str], conversation: Optional[List[Tuple[str, str]]], st
 
                 history[-1]["model"] = chunk.model
                 if chunk.choices[0].delta.content:
+                    if not history[-1]["content"]:
+                        history[-1]["content"] = ""
                     history[-1]["content"] = (
                         history[-1]["content"] + chunk.choices[0].delta.content
                     )
-                history[-1]["tool_calls"] = chunk.choices[0].delta.tool_calls
+                if chunk.choices[0].delta.tool_calls:
+                    history[-1]["tool_calls"] = chunk.choices[0].delta.tool_calls
 
                 if chunk.model and chunk.choices[0].delta.content:
                     messages[-1] = (
diff --git a/crates/prompt_gateway/src/stream_context.rs b/crates/prompt_gateway/src/stream_context.rs
index 6ababa70..c4a15f47 100644
--- a/crates/prompt_gateway/src/stream_context.rs
+++ b/crates/prompt_gateway/src/stream_context.rs
@@ -688,6 +688,7 @@ impl StreamContext {
 
             if self.streaming_response {}
 
+            self.tool_calls = None;
             return self.send_http_response(
                 StatusCode::OK.as_u16().into(),
                 vec![("Powered-By", "Katanemo")],