diff --git a/src/engine/platform/fmshared_OPN.h b/src/engine/platform/fmshared_OPN.h
index 769a1814b..6ab448e6d 100644
--- a/src/engine/platform/fmshared_OPN.h
+++ b/src/engine/platform/fmshared_OPN.h
@@ -83,6 +83,8 @@
     return 2; \
   }
 
+#define IS_EXTCH_MUTED (isOpMuted[0] && isOpMuted[1] && isOpMuted[2] && isOpMuted[3])
+
 class DivPlatformOPN: public DivPlatformFMBase {
   protected:
     const unsigned short ADDR_MULT_DT=0x30;
diff --git a/src/engine/platform/genesisext.cpp b/src/engine/platform/genesisext.cpp
index 6443729ff..8e16071af 100644
--- a/src/engine/platform/genesisext.cpp
+++ b/src/engine/platform/genesisext.cpp
@@ -25,7 +25,6 @@
 #define CHIP_DIVIDER fmDivBase
 
 #define IS_REALLY_MUTED(x) (isMuted[x] && (x<5 || !softPCM || (isMuted[5] && isMuted[6])))
-#define IS_EXTCH_MUTED (isOpMuted[0] && isOpMuted[1] && isOpMuted[2] && isOpMuted[3])
 
 int DivPlatformGenesisExt::dispatch(DivCommand c) {
   if (c.chan<2) {
diff --git a/src/engine/platform/ym2203ext.cpp b/src/engine/platform/ym2203ext.cpp
index f4ad294fa..b8c40f68c 100644
--- a/src/engine/platform/ym2203ext.cpp
+++ b/src/engine/platform/ym2203ext.cpp
@@ -45,8 +45,6 @@ int DivPlatformYM2203Ext::dispatch(DivCommand c) {
       if (opChan[ch].insChanged) {
         chan[2].state.alg=ins->fm.alg;
         chan[2].state.fb=ins->fm.fb;
-        chan[2].state.fms=ins->fm.fms;
-        chan[2].state.ams=ins->fm.ams;
         chan[2].state.op[ordch]=ins->fm.op[ordch];
       }
 
@@ -80,7 +78,6 @@ int DivPlatformYM2203Ext::dispatch(DivCommand c) {
       }
       if (opChan[ch].insChanged) { // TODO how does this work?
         rWrite(chanOffs[2]+0xb0,(chan[2].state.alg&7)|(chan[2].state.fb<<3));
-        rWrite(chanOffs[2]+0xb4,(IS_EXTCH_MUTED?0:(opChan[ch].pan<<6))|(chan[2].state.fms&7)|((chan[2].state.ams&3)<<4));
       }
       opChan[ch].insChanged=false;