diff --git a/Modem/afsk.c b/Modem/afsk.c
index 08de92c..b16ffa1 100644
--- a/Modem/afsk.c
+++ b/Modem/afsk.c
@@ -281,8 +281,8 @@ void afsk_adc_isr(Afsk *afsk, int8_t currentSample) {
 
 	afsk->iirY[0] = afsk->iirY[1];
 	
-	af->iirY[1] = af->iirX[0] + af->iirX[1] + (af->iirY[0] >> 1) + (af->iirY[0] >> 3) + (af->iirY[0] >> 5); // Butterworth
-	//afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] >> 1); // Chebyshev
+	//af->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] >> 1) + (afsk->iirY[0] >> 3) + (afsk->iirY[0] >> 5); // Butterworth
+	afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] >> 1); // Chebyshev
 
 
 	// We put the sampled bit in a delay-line:
diff --git a/buildrev.h b/buildrev.h
index 58741bc..e1d8ca6 100644
--- a/buildrev.h
+++ b/buildrev.h
@@ -1,2 +1,2 @@
-#define VERS_BUILD 438
+#define VERS_BUILD 439
 #define VERS_HOST  "vixen"