diff --git a/src/engine/platform/genesis.cpp b/src/engine/platform/genesis.cpp
index e85bc7688..f00a521bc 100644
--- a/src/engine/platform/genesis.cpp
+++ b/src/engine/platform/genesis.cpp
@@ -493,8 +493,10 @@ int DivPlatformGenesis::dispatch(DivCommand c) {
           }
           dacPos=0;
           dacPeriod=0;
-          chan[c.chan].baseFreq=NOTE_FREQUENCY(c.value);
-          chan[c.chan].freqChanged=true;
+          if (c.value!=DIV_NOTE_NULL) {
+            chan[c.chan].baseFreq=NOTE_FREQUENCY(c.value);
+            chan[c.chan].freqChanged=true;
+          }
           chan[c.chan].furnaceDac=true;
         } else { // compatible mode
           if (c.value!=DIV_NOTE_NULL) {
diff --git a/src/engine/platform/nes.cpp b/src/engine/platform/nes.cpp
index 9f56e4e56..e99a3e29e 100644
--- a/src/engine/platform/nes.cpp
+++ b/src/engine/platform/nes.cpp
@@ -274,8 +274,8 @@ int DivPlatformNES::dispatch(DivCommand c) {
           }
           dacPos=0;
           dacPeriod=0;
-          chan[c.chan].baseFreq=parent->song.tuning*pow(2.0f,((float)(c.value+3)/12.0f));
           if (c.value!=DIV_NOTE_NULL) {
+            chan[c.chan].baseFreq=parent->song.tuning*pow(2.0f,((float)(c.value+3)/12.0f));
             chan[c.chan].freqChanged=true;
             chan[c.chan].note=c.value;
           }
diff --git a/src/engine/platform/segapcm.cpp b/src/engine/platform/segapcm.cpp
index b87ee9a86..84ec00c37 100644
--- a/src/engine/platform/segapcm.cpp
+++ b/src/engine/platform/segapcm.cpp
@@ -142,8 +142,10 @@ int DivPlatformSegaPCM::dispatch(DivCommand c) {
           break;
         }
         chan[c.chan].pcm.pos=0;
-        chan[c.chan].baseFreq=(c.value<<6);
-        chan[c.chan].freqChanged=true;
+        if (c.value!=DIV_NOTE_NULL) {
+          chan[c.chan].baseFreq=(c.value<<6);
+          chan[c.chan].freqChanged=true;
+        }
         chan[c.chan].furnacePCM=true;
         if (dumpWrites) { // Sega PCM writes
           DivSample* s=parent->getSample(chan[c.chan].pcm.sample);