diff --git a/src/pipecat/frames/frames.py b/src/pipecat/frames/frames.py
index 335b92753..542f21fc0 100644
--- a/src/pipecat/frames/frames.py
+++ b/src/pipecat/frames/frames.py
@@ -516,6 +516,7 @@ class TranscriptionMessage:
 class ThoughtTranscriptionMessage:
     """An LLM thought message in a conversation transcript."""
 
+    role: Literal["assistant"] = field(default="assistant", init=False)
     content: str
     timestamp: Optional[str] = None