diff --git a/src/engine/platform/vic20.cpp b/src/engine/platform/vic20.cpp
index 253c4fb7..aea12643 100644
--- a/src/engine/platform/vic20.cpp
+++ b/src/engine/platform/vic20.cpp
@@ -79,7 +79,7 @@ void DivPlatformVIC20::calcAndWriteOutVol(int ch, int env) {
 }
 
 void DivPlatformVIC20::writeOutVol(int ch) {
-  if (!isMuted[ch] && chan[ch].active) {
+  if (chan[ch].active) {
     rWrite(14,chan[ch].outVol);
   }
 }
@@ -99,6 +99,20 @@ void DivPlatformVIC20::tick(bool sysTick) {
       }
       chan[i].freqChanged=true;
     }
+    if (chan[i].std.duty.had) {
+      if (chan[i].onOff!=chan[i].std.duty.val) {
+        chan[i].onOff=chan[i].std.duty.val;
+        if (chan[i].active) {
+          if (chan[i].onOff) {
+            chan[i].keyOn=true;
+            chan[i].keyOff=false;
+          } else {
+            chan[i].keyOn=false;
+            chan[i].keyOff=true;
+          }
+        }
+      }
+    }
     if (chan[i].std.wave.had) {
       if (chan[i].wave!=chan[i].std.wave.val) {
         chan[i].wave=chan[i].std.wave.val&0x0f;
@@ -156,6 +170,7 @@ int DivPlatformVIC20::dispatch(DivCommand c) {
         chan[c.chan].freqChanged=true;
         chan[c.chan].note=c.value;
       }
+      chan[c.chan].onOff=true;
       chan[c.chan].active=true;
       chan[c.chan].keyOn=true;
       chan[c.chan].macroInit(ins);
diff --git a/src/engine/platform/vic20.h b/src/engine/platform/vic20.h
index 1b8584a7..5125bd96 100644
--- a/src/engine/platform/vic20.h
+++ b/src/engine/platform/vic20.h
@@ -27,10 +27,12 @@
 class DivPlatformVIC20: public DivDispatch {
   struct Channel: public SharedChannel<int> {
     int wave, waveWriteCycle;
+    bool onOff;
     Channel():
       SharedChannel<int>(15),
       wave(0),
-      waveWriteCycle(-1) {}
+      waveWriteCycle(-1),
+      onOff(true) {}
   };
   Channel chan[4];
   DivDispatchOscBuffer* oscBuf[4];
diff --git a/src/gui/insEdit.cpp b/src/gui/insEdit.cpp
index 1f9951da..1b16e2dc 100644
--- a/src/gui/insEdit.cpp
+++ b/src/gui/insEdit.cpp
@@ -5125,7 +5125,7 @@ void FurnaceGUI::drawInsEdit() {
             dutyMax=ins->amiga.useSample?0:255;
           }
           if (ins->type==DIV_INS_TIA || ins->type==DIV_INS_AMIGA || ins->type==DIV_INS_SCC ||
-              ins->type==DIV_INS_PET || ins->type==DIV_INS_VIC || ins->type==DIV_INS_SEGAPCM ||
+              ins->type==DIV_INS_PET || ins->type==DIV_INS_SEGAPCM ||
               ins->type==DIV_INS_FM || ins->type==DIV_INS_K007232 || ins->type==DIV_INS_GA20 ||
               ins->type==DIV_INS_SM8521 || ins->type==DIV_INS_PV1000) {
             dutyMax=0;
@@ -5142,6 +5142,10 @@ void FurnaceGUI::drawInsEdit() {
             dutyLabel="Noise";
             dutyMax=1;
           }
+          if (ins->type==DIV_INS_VIC) {
+            dutyLabel="On/Off";
+            dutyMax=1;
+          }
           if (ins->type==DIV_INS_SWAN) {
             dutyLabel="Noise";
             dutyMax=ins->amiga.useSample?0:8;