diff --git a/src/engine/platform/nes.cpp b/src/engine/platform/nes.cpp
index a91f7827e..a2cb58abb 100644
--- a/src/engine/platform/nes.cpp
+++ b/src/engine/platform/nes.cpp
@@ -145,7 +145,9 @@ void DivPlatformNES::tick() {
         if ((chan[i].prevFreq>>8)!=(chan[i].freq>>8) || i==2) {
           apu_wr_reg(0x4003+i*4,0xf8|(chan[i].freq>>8));
         }
-        chan[i].prevFreq=chan[i].freq;
+        if (chan[i].freq!=65535 && chan[i].freq!=0) {
+          chan[i].prevFreq=chan[i].freq;
+        }
       }
       if (chan[i].keyOn) chan[i].keyOn=false;
       if (chan[i].keyOff) chan[i].keyOff=false;
diff --git a/src/engine/platform/nes.h b/src/engine/platform/nes.h
index 490971c2b..5d61b9b81 100644
--- a/src/engine/platform/nes.h
+++ b/src/engine/platform/nes.h
@@ -28,6 +28,7 @@ class DivPlatformNES: public DivDispatch {
       keyOff(false),
       inPorta(false),
       vol(15),
+      outVol(15),
       wave(-1) {}
   };
   Channel chan[5];
diff --git a/src/engine/platform/sms.h b/src/engine/platform/sms.h
index eeaed1217..85af8dbfb 100644
--- a/src/engine/platform/sms.h
+++ b/src/engine/platform/sms.h
@@ -23,7 +23,8 @@ class DivPlatformSMS: public DivDispatch {
       freqChanged(false),
       keyOn(false),
       keyOff(false),
-      vol(15) {}
+      vol(15),
+      outVol(15) {}
   };
   Channel chan[4];
   unsigned char snNoiseMode;