diff --git a/src/engine/platform/arcade.cpp b/src/engine/platform/arcade.cpp
index 7d44fe8a8..6e925c9a0 100644
--- a/src/engine/platform/arcade.cpp
+++ b/src/engine/platform/arcade.cpp
@@ -255,6 +255,10 @@ void DivPlatformArcade::tick(bool sysTick) {
       chan[i].state.ams=chan[i].std.ams.val;
       rWrite(chanOffs[i]+ADDR_FMS_AMS,((chan[i].state.fms&7)<<4)|(chan[i].state.ams&3));
     }
+    if (chan[i].std.ex4.had && chan[i].active) {
+      chan[i].opMask=chan[i].std.ex4.val&15;
+      chan[i].opMaskChanged=true;
+    }
     for (int j=0; j<4; j++) {
       unsigned short baseAddr=chanOffs[i]|opOffs[j];
       DivInstrumentFM::Operator& op=chan[i].state.op[j];
@@ -347,8 +351,9 @@ void DivPlatformArcade::tick(bool sysTick) {
       immWrite(i+0x30,chan[i].freq<<2);
       chan[i].freqChanged=false;
     }
-    if (chan[i].keyOn) {
+    if (chan[i].keyOn || chan[i].opMaskChanged) {
       immWrite(0x08,(chan[i].opMask<<3)|i);
+      chan[i].opMaskChanged=false;
       chan[i].keyOn=false;
     }
   }
diff --git a/src/engine/platform/arcade.h b/src/engine/platform/arcade.h
index 683394e3b..2a9c2b40c 100644
--- a/src/engine/platform/arcade.h
+++ b/src/engine/platform/arcade.h
@@ -43,7 +43,7 @@ class DivPlatformArcade: public DivPlatformOPM {
       int freq, baseFreq, pitch, pitch2, note;
       int ins;
       signed char konCycles;
-      bool active, insChanged, freqChanged, keyOn, keyOff, inPorta, portaPause, furnacePCM, hardReset;
+      bool active, insChanged, freqChanged, keyOn, keyOff, inPorta, portaPause, furnacePCM, hardReset, opMaskChanged;
       int vol, outVol;
       unsigned char chVolL, chVolR, opMask;
       void macroInit(DivInstrument* which) {
@@ -68,6 +68,7 @@ class DivPlatformArcade: public DivPlatformOPM {
         portaPause(false),
         furnacePCM(false),
         hardReset(false),
+        opMaskChanged(false),
         vol(0),
         outVol(0),
         chVolL(127),
diff --git a/src/engine/platform/ym2203.cpp b/src/engine/platform/ym2203.cpp
index 46696b8ac..1c3488006 100644
--- a/src/engine/platform/ym2203.cpp
+++ b/src/engine/platform/ym2203.cpp
@@ -273,6 +273,10 @@ void DivPlatformYM2203::tick(bool sysTick) {
       chan[i].state.fb=chan[i].std.fb.val;
       rWrite(chanOffs[i]+ADDR_FB_ALG,(chan[i].state.alg&7)|(chan[i].state.fb<<3));
     }
+    if (chan[i].std.ex4.had && chan[i].active) {
+      chan[i].opMask=chan[i].std.ex4.val&15;
+      chan[i].opMaskChanged=true;
+    }
     for (int j=0; j<4; j++) {
       unsigned short baseAddr=chanOffs[i]|opOffs[j];
       DivInstrumentFM::Operator& op=chan[i].state.op[j];
@@ -385,8 +389,9 @@ void DivPlatformYM2203::tick(bool sysTick) {
       immWrite(chanOffs[i]+ADDR_FREQ,chan[i].freq&0xff);
       chan[i].freqChanged=false;
     }
-    if (chan[i].keyOn) {
+    if (chan[i].keyOn || chan[i].opMaskChanged) {
       immWrite(0x28,(chan[i].opMask<<4)|konOffs[i]);
+      chan[i].opMaskChanged=false;
       chan[i].keyOn=false;
     }
   }
diff --git a/src/engine/platform/ym2203.h b/src/engine/platform/ym2203.h
index 921c1d94b..756603651 100644
--- a/src/engine/platform/ym2203.h
+++ b/src/engine/platform/ym2203.h
@@ -45,7 +45,7 @@ class DivPlatformYM2203: public DivPlatformOPN {
       int freq, baseFreq, pitch, pitch2, portaPauseFreq, note, ins;
       unsigned char psgMode, autoEnvNum, autoEnvDen, opMask;
       signed char konCycles;
-      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, inPorta, furnacePCM, hardReset;
+      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, inPorta, furnacePCM, hardReset, opMaskChanged;
       int vol, outVol;
       int sample;
       DivMacroInt std;
@@ -76,6 +76,7 @@ class DivPlatformYM2203: public DivPlatformOPN {
         inPorta(false),
         furnacePCM(false),
         hardReset(false),
+        opMaskChanged(false),
         vol(0),
         outVol(15),
         sample(-1) {}
diff --git a/src/engine/platform/ym2608.cpp b/src/engine/platform/ym2608.cpp
index 801bab329..ec90c1c6b 100644
--- a/src/engine/platform/ym2608.cpp
+++ b/src/engine/platform/ym2608.cpp
@@ -441,6 +441,10 @@ void DivPlatformYM2608::tick(bool sysTick) {
       chan[i].state.ams=chan[i].std.ams.val;
       rWrite(chanOffs[i]+ADDR_LRAF,(isMuted[i]?0:(chan[i].pan<<6))|(chan[i].state.fms&7)|((chan[i].state.ams&3)<<4));
     }
+    if (chan[i].std.ex4.had && chan[i].active) {
+      chan[i].opMask=chan[i].std.ex4.val&15;
+      chan[i].opMaskChanged=true;
+    }
     for (int j=0; j<4; j++) {
       unsigned short baseAddr=chanOffs[i]|opOffs[j];
       DivInstrumentFM::Operator& op=chan[i].state.op[j];
@@ -581,8 +585,9 @@ void DivPlatformYM2608::tick(bool sysTick) {
       immWrite(chanOffs[i]+ADDR_FREQ,chan[i].freq&0xff);
       chan[i].freqChanged=false;
     }
-    if (chan[i].keyOn) {
+    if (chan[i].keyOn || chan[i].opMaskChanged) {
       immWrite(0x28,(chan[i].opMask<<4)|konOffs[i]);
+      chan[i].opMaskChanged=false;
       chan[i].keyOn=false;
     }
   }
diff --git a/src/engine/platform/ym2608.h b/src/engine/platform/ym2608.h
index 1689436ee..ed850bf85 100644
--- a/src/engine/platform/ym2608.h
+++ b/src/engine/platform/ym2608.h
@@ -50,7 +50,7 @@ class DivPlatformYM2608: public DivPlatformOPN {
       int freq, baseFreq, pitch, pitch2, portaPauseFreq, note, ins;
       unsigned char psgMode, autoEnvNum, autoEnvDen, opMask;
       signed char konCycles;
-      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, inPorta, furnacePCM, hardReset;
+      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, inPorta, furnacePCM, hardReset, opMaskChanged;
       int vol, outVol;
       int sample;
       unsigned char pan;
@@ -82,6 +82,7 @@ class DivPlatformYM2608: public DivPlatformOPN {
         inPorta(false),
         furnacePCM(false),
         hardReset(false),
+        opMaskChanged(false),
         vol(0),
         outVol(15),
         sample(-1),
diff --git a/src/engine/platform/ym2610.cpp b/src/engine/platform/ym2610.cpp
index 63a6d72e3..6a8509d55 100644
--- a/src/engine/platform/ym2610.cpp
+++ b/src/engine/platform/ym2610.cpp
@@ -482,6 +482,10 @@ void DivPlatformYM2610::tick(bool sysTick) {
       chan[i].state.ams=chan[i].std.ams.val;
       rWrite(chanOffs[i]+ADDR_LRAF,(isMuted[i]?0:(chan[i].pan<<6))|(chan[i].state.fms&7)|((chan[i].state.ams&3)<<4));
     }
+    if (chan[i].std.ex4.had && chan[i].active) {
+      chan[i].opMask=chan[i].std.ex4.val&15;
+      chan[i].opMaskChanged=true;
+    }
     for (int j=0; j<4; j++) {
       unsigned short baseAddr=chanOffs[i]|opOffs[j];
       DivInstrumentFM::Operator& op=chan[i].state.op[j];
@@ -618,8 +622,9 @@ void DivPlatformYM2610::tick(bool sysTick) {
       immWrite(chanOffs[i]+ADDR_FREQ,chan[i].freq&0xff);
       chan[i].freqChanged=false;
     }
-    if (chan[i].keyOn) {
+    if (chan[i].keyOn || chan[i].opMaskChanged) {
       immWrite(0x28,(chan[i].opMask<<4)|konOffs[i]);
+      chan[i].opMaskChanged=false;
       chan[i].keyOn=false;
     }
   }
diff --git a/src/engine/platform/ym2610.h b/src/engine/platform/ym2610.h
index 0e363329a..4f1a16642 100644
--- a/src/engine/platform/ym2610.h
+++ b/src/engine/platform/ym2610.h
@@ -73,7 +73,7 @@ class DivPlatformYM2610: public DivPlatformYM2610Base {
       int freq, baseFreq, pitch, pitch2, portaPauseFreq, note, ins;
       unsigned char psgMode, autoEnvNum, autoEnvDen;
       signed char konCycles;
-      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, inPorta, furnacePCM, hardReset;
+      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, inPorta, furnacePCM, hardReset, opMaskChanged;
       int vol, outVol;
       int sample;
       unsigned char pan, opMask;
@@ -104,6 +104,7 @@ class DivPlatformYM2610: public DivPlatformYM2610Base {
         inPorta(false),
         furnacePCM(false),
         hardReset(false),
+        opMaskChanged(false),
         vol(0),
         outVol(15),
         sample(-1),
diff --git a/src/engine/platform/ym2610b.cpp b/src/engine/platform/ym2610b.cpp
index f01f39b42..31cd7b3ff 100644
--- a/src/engine/platform/ym2610b.cpp
+++ b/src/engine/platform/ym2610b.cpp
@@ -465,6 +465,10 @@ void DivPlatformYM2610B::tick(bool sysTick) {
       chan[i].state.ams=chan[i].std.ams.val;
       rWrite(chanOffs[i]+ADDR_LRAF,(isMuted[i]?0:(chan[i].pan<<6))|(chan[i].state.fms&7)|((chan[i].state.ams&3)<<4));
     }
+    if (chan[i].std.ex4.had && chan[i].active) {
+      chan[i].opMask=chan[i].std.ex4.val&15;
+      chan[i].opMaskChanged=true;
+    }
     for (int j=0; j<4; j++) {
       unsigned short baseAddr=chanOffs[i]|opOffs[j];
       DivInstrumentFM::Operator& op=chan[i].state.op[j];
@@ -600,8 +604,9 @@ void DivPlatformYM2610B::tick(bool sysTick) {
       immWrite(chanOffs[i]+ADDR_FREQ,chan[i].freq&0xff);
       chan[i].freqChanged=false;
     }
-    if (chan[i].keyOn) {
+    if (chan[i].keyOn || chan[i].opMaskChanged) {
       immWrite(0x28,(chan[i].opMask<<4)|konOffs[i]);
+      chan[i].opMaskChanged=false;
       chan[i].keyOn=false;
     }
   }
diff --git a/src/engine/platform/ym2610b.h b/src/engine/platform/ym2610b.h
index 87500e9b0..1d5fc1f31 100644
--- a/src/engine/platform/ym2610b.h
+++ b/src/engine/platform/ym2610b.h
@@ -40,7 +40,7 @@ class DivPlatformYM2610B: public DivPlatformYM2610Base {
       int freq, baseFreq, pitch, pitch2, portaPauseFreq, note, ins;
       unsigned char psgMode, autoEnvNum, autoEnvDen;
       signed char konCycles;
-      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, inPorta, furnacePCM, hardReset;
+      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, inPorta, furnacePCM, hardReset, opMaskChanged;
       int vol, outVol;
       int sample;
       unsigned char pan, opMask;
@@ -71,6 +71,7 @@ class DivPlatformYM2610B: public DivPlatformYM2610Base {
         inPorta(false),
         furnacePCM(false),
         hardReset(false),
+        opMaskChanged(false),
         vol(0),
         outVol(15),
         sample(-1),