diff --git a/rtcllm/vad.py b/rtcllm/vad.py
index e381a28..02f1f43 100644
--- a/rtcllm/vad.py
+++ b/rtcllm/vad.py
@@ -146,7 +146,7 @@ class AudioTrackVad(MediaStreamTrack):
 	def stop(self):
 		self.running = False
 
-	def to16000_160_frames(frame):
+	def to16000_160_frames(self, frame):
 		frames = resample(frame, sample_rate=16000)
 		ret_frames = []
 		for f in frames: