diff --git a/sherpa-onnx/csrc/voice-activity-detector.cc b/sherpa-onnx/csrc/voice-activity-detector.cc
index b3374c8ee..f3d5178ee 100644
--- a/sherpa-onnx/csrc/voice-activity-detector.cc
+++ b/sherpa-onnx/csrc/voice-activity-detector.cc
@@ -277,7 +277,7 @@ class VoiceActivityDetector::Impl {
   void Flush() {
     int32_t buffer_size = buffer_.Size();
 
-    if (buffer_size > 0) {
+    if (buffer_size >= window_size) {
       std::vector<float> s = buffer_.Get(buffer_.Head(), buffer_size);
       SpeechSegment segment;
       segment.start = current_sample;