diff --git a/python/packages/autogen-ext/src/autogen_ext/models/openai/_openai_client.py b/python/packages/autogen-ext/src/autogen_ext/models/openai/_openai_client.py
index db5fd911302..6f032a3393b 100644
--- a/python/packages/autogen-ext/src/autogen_ext/models/openai/_openai_client.py
+++ b/python/packages/autogen-ext/src/autogen_ext/models/openai/_openai_client.py
@@ -558,8 +558,8 @@ async def create(
             logprobs=logprobs,
         )
 
-        _add_usage(self._actual_usage, usage)
-        _add_usage(self._total_usage, usage)
+        self._total_usage = _add_usage(self._total_usage, usage)
+        self._actual_usage = _add_usage(self._actual_usage, usage)
 
         # TODO - why is this cast needed?
         return response
@@ -775,8 +775,8 @@ async def create_stream(
             logprobs=logprobs,
         )
 
-        _add_usage(self._actual_usage, usage)
-        _add_usage(self._total_usage, usage)
+        self._total_usage = _add_usage(self._total_usage, usage)
+        self._actual_usage = _add_usage(self._actual_usage, usage)
 
         yield result