diff --git a/src/engine/platform/c64.cpp b/src/engine/platform/c64.cpp
index 4d1caf9ab..d52a5dd00 100644
--- a/src/engine/platform/c64.cpp
+++ b/src/engine/platform/c64.cpp
@@ -148,7 +148,7 @@ void DivPlatformC64::tick(bool sysTick) {
     if (chan[i].std.pitch.had) {
       if (chan[i].std.pitch.mode) {
         chan[i].pitch2+=chan[i].std.pitch.val;
-        CLAMP_VAR(chan[i].pitch2,-32768,32767);
+        CLAMP_VAR(chan[i].pitch2,-65535,65535);
       } else {
         chan[i].pitch2=chan[i].std.pitch.val;
       }
@@ -188,6 +188,7 @@ void DivPlatformC64::tick(bool sysTick) {
 
     if (chan[i].freqChanged || chan[i].keyOn || chan[i].keyOff) {
       chan[i].freq=parent->calcFreq(chan[i].baseFreq,chan[i].pitch,chan[i].fixedArp?chan[i].baseNoteOverride:chan[i].arpOff,chan[i].fixedArp,false,8,chan[i].pitch2,chipClock,CHIP_FREQBASE);
+      if (chan[i].freq<0) chan[i].freq=0;
       if (chan[i].freq>0xffff) chan[i].freq=0xffff;
       if (chan[i].keyOn) {
         rWrite(i*7+5,(chan[i].attack<<4)|(chan[i].decay));