diff --git a/src/agents/tracing/span_data.py b/src/agents/tracing/span_data.py
index f4817ea98c..39d3a2a58c 100644
--- a/src/agents/tracing/span_data.py
+++ b/src/agents/tracing/span_data.py
@@ -405,7 +405,7 @@ class SpeechGroupSpanData(SpanData):
     Represents a Speech Group Span in the trace.
     """
 
-    __slots__ = "input"
+    __slots__ = ("input",)
 
     def __init__(
         self,