diff --git a/main.go b/main.go
index e5d07c4..8bb82a9 100644
--- a/main.go
+++ b/main.go
@@ -101,7 +101,7 @@ func (g *Game) Draw(screen *ebiten.Image) {
 			binary.Read(audio.SampleRingBuffer, binary.NativeEndian, &AX)
 			binary.Read(audio.SampleRingBuffer, binary.NativeEndian, &AY)
 		}
-		FFTBuffer = window.Apply(FFTBuffer, signalprocessing.CachedWindowFunction)
+		window.Apply(FFTBuffer, signalprocessing.CachedWindowFunction)
 		X := fft.FFTReal(FFTBuffer)
 		r, θ := cmplx.Polar(X[1])
 		maxR := r