diff --git a/src/engine/platform/genesisext.cpp b/src/engine/platform/genesisext.cpp
index 5c9d986a4..cc763d098 100644
--- a/src/engine/platform/genesisext.cpp
+++ b/src/engine/platform/genesisext.cpp
@@ -589,6 +589,7 @@ void DivPlatformGenesisExt::tick(bool sysTick) {
       if (opChan[i].freq>0x3fff) opChan[i].freq=0x3fff;
       immWrite(opChanOffsH[i],opChan[i].freq>>8);
       immWrite(opChanOffsL[i],opChan[i].freq&0xff);
+      opChan[i].freqChanged=false;
     }
     writeMask|=(unsigned char)(opChan[i].mask && opChan[i].active)<<(4+i);
     if (opChan[i].keyOn) {