diff --git a/langfuse/openai.py b/langfuse/openai.py
index 59e7e6c2a..c3cfe707a 100644
--- a/langfuse/openai.py
+++ b/langfuse/openai.py
@@ -558,7 +558,7 @@ def _extract_streamed_openai_response(resource, chunks):
                         )
 
             if resource.type == "completion":
-                completion += choice.get("text", None)
+                completion += choice.get("text", "")
 
     def get_response_for_chat():
         return (