diff --git a/src/engine/engine.cpp b/src/engine/engine.cpp
index 4ee8e48bb..153a8db97 100644
--- a/src/engine/engine.cpp
+++ b/src/engine/engine.cpp
@@ -1713,7 +1713,11 @@ int DivEngine::calcFreq(int base, int pitch, bool period, int octave, int pitch2
 }
 
 int DivEngine::calcArp(int note, int arp, int offset) {
-  if (arp&0x40000000) return (arp&(~0x40000000))+offset;
+  if (arp<0) {
+    if (!(arp&0x40000000)) return (arp|0x40000000)+offset;
+  } else {
+    if (arp&0x40000000) return (arp&(~0x40000000))+offset;
+  }
   return note+arp;
 }
 
diff --git a/src/engine/fileOps.cpp b/src/engine/fileOps.cpp
index c2acd45d4..506dfc6f9 100644
--- a/src/engine/fileOps.cpp
+++ b/src/engine/fileOps.cpp
@@ -510,9 +510,9 @@ bool DivEngine::loadDMF(unsigned char* file, size_t len) {
         } else {
           ins->std.arpMacro.mode=0;
           for (int j=0; j<ins->std.arpMacro.len; j++) {
-            ins->std.arpMacro.val[i]|=0x40000000;
+            ins->std.arpMacro.val[j]^=0x40000000;
           }
-          if (ins->std.arpMacro.loop<ins->std.arpMacro.len && ins->std.arpMacro.len<255) {
+          if (ins->std.arpMacro.loop>=ins->std.arpMacro.len && ins->std.arpMacro.len<255) {
             ins->std.arpMacro.val[ins->std.arpMacro.len++]=0;
           }
         }
@@ -2928,7 +2928,7 @@ bool DivEngine::loadFC(unsigned char* file, size_t len) {
             logV("unhandled pitch!");
           } else {
             if (fm.val[j]>0x80) {
-              ins->std.arpMacro.val[ins->std.arpMacro.len]=(fm.val[j]-0x80+24)|0x40000000;
+              ins->std.arpMacro.val[ins->std.arpMacro.len]=(fm.val[j]-0x80+24)^0x40000000;
             } else {
               ins->std.arpMacro.val[ins->std.arpMacro.len]=fm.val[j];
             }
diff --git a/src/engine/instrument.cpp b/src/engine/instrument.cpp
index bd28834c4..430e361ae 100644
--- a/src/engine/instrument.cpp
+++ b/src/engine/instrument.cpp
@@ -1347,9 +1347,9 @@ DivDataErrors DivInstrument::readInsData(SafeReader& reader, short version) {
     if (std.arpMacro.mode) {
       std.arpMacro.mode=0;
       for (int i=0; i<std.arpMacro.len; i++) {
-        std.arpMacro.val[i]|=0x40000000;
+        std.arpMacro.val[i]^=0x40000000;
       }
-      if (std.arpMacro.loop<std.arpMacro.len && std.arpMacro.rel>std.arpMacro.loop && std.arpMacro.len<255) {
+      if ((std.arpMacro.loop>=std.arpMacro.len || std.arpMacro.rel>std.arpMacro.loop) && std.arpMacro.len<255) {
         std.arpMacro.val[std.arpMacro.len++]=0;
       }
     }
diff --git a/src/engine/platform/gb.cpp b/src/engine/platform/gb.cpp
index afed615d2..fea89c71d 100644
--- a/src/engine/platform/gb.cpp
+++ b/src/engine/platform/gb.cpp
@@ -169,7 +169,7 @@ void DivPlatformGB::tick(bool sysTick) {
         if (chan[i].baseFreq>255) chan[i].baseFreq=255;
         if (chan[i].baseFreq<0) chan[i].baseFreq=0;
       } else {
-        chan[i].baseFreq=NOTE_PERIODIC(parent->calcArp(chan[i].note,chan[i].std.arp.val));
+        chan[i].baseFreq=NOTE_PERIODIC(parent->calcArp(chan[i].note,chan[i].std.arp.val,24));
       }
       chan[i].freqChanged=true;
     }
diff --git a/src/engine/platform/tia.cpp b/src/engine/platform/tia.cpp
index fe7273a1c..d55200f9f 100644
--- a/src/engine/platform/tia.cpp
+++ b/src/engine/platform/tia.cpp
@@ -90,7 +90,9 @@ void DivPlatformTIA::tick(bool sysTick) {
     // TODO: the way arps work on TIA is really weird
     if (chan[i].std.arp.had) {
       if (!chan[i].inPorta) {
-        if (chan[i].std.arp.val&0x40000000) {
+        if (chan[i].std.arp.val<0 && (!(chan[i].std.arp.val&0x40000000))) {
+          chan[i].baseFreq=0x80000000|(chan[i].std.arp.val|0x40000000);
+        } else if (chan[i].std.arp.val&0x40000000) {
           chan[i].baseFreq=0x80000000|(chan[i].std.arp.val&(~0x40000000));
         } else {
           chan[i].baseFreq=(chan[i].note+chan[i].std.arp.val)<<8;
diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index c044ae664..8ea22a144 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -201,8 +201,13 @@ void FurnaceGUI::encodeMMLStr(String& target, int* macro, int macroLen, int macr
   for (int i=0; i<macroLen; i++) {
     if (i==macroLoop) target+="| ";
     if (i==macroRel) target+="/ ";
-    if (bit30 && macro[i]&0x40000000) target+="@";
-    int macroVal=macro[i]&(bit30?(~0x40000000):0xffffffff);
+    if (bit30 && ((macro[i]&0xc0000000)==0x40000000 || (macro[i]&0xc0000000)==0x80000000)) target+="@";
+    int macroVal=macro[i];
+    if (macro[i]<0) {
+      if (!(macroVal&0x40000000)) macroVal|=0x40000000;
+    } else {
+      if (macroVal&0x40000000) macroVal&=~0x40000000;
+    }
     if (hex) {
       if (i==macroLen-1) {
         snprintf(buf,31,"%.2X",macroVal);
@@ -312,7 +317,7 @@ void FurnaceGUI::decodeMMLStr(String& source, int* macro, unsigned char& macroLe
           negaBuf=false;
           if (macro[macroLen]<macroMin) macro[macroLen]=macroMin;
           if (macro[macroLen]>macroMax) macro[macroLen]=macroMax;
-          if (setBit30) macro[macroLen]|=0x40000000;
+          if (setBit30) macro[macroLen]^=0x40000000;
           setBit30=false;
           macroLen++;
           buf=0;
@@ -325,7 +330,7 @@ void FurnaceGUI::decodeMMLStr(String& source, int* macro, unsigned char& macroLe
           negaBuf=false;
           if (macro[macroLen]<macroMin) macro[macroLen]=macroMin;
           if (macro[macroLen]>macroMax) macro[macroLen]=macroMax;
-          if (setBit30) macro[macroLen]|=0x40000000;
+          if (setBit30) macro[macroLen]^=0x40000000;
           setBit30=false;
           macroLen++;
           buf=0;
@@ -341,7 +346,7 @@ void FurnaceGUI::decodeMMLStr(String& source, int* macro, unsigned char& macroLe
           negaBuf=false;
           if (macro[macroLen]<macroMin) macro[macroLen]=macroMin;
           if (macro[macroLen]>macroMax) macro[macroLen]=macroMax;
-          if (setBit30) macro[macroLen]|=0x40000000;
+          if (setBit30) macro[macroLen]^=0x40000000;
           setBit30=false;
           macroLen++;
           buf=0;
@@ -359,7 +364,7 @@ void FurnaceGUI::decodeMMLStr(String& source, int* macro, unsigned char& macroLe
     negaBuf=false;
     if (macro[macroLen]<macroMin) macro[macroLen]=macroMin;
     if (macro[macroLen]>macroMax) macro[macroLen]=macroMax;
-    if (setBit30) macro[macroLen]|=0x40000000;
+    if (setBit30) macro[macroLen]^=0x40000000;
     setBit30=false;
     macroLen++;
     buf=0;
@@ -1774,7 +1779,8 @@ void FurnaceGUI::showError(String what) {
   displayError=true;
 }
 
-#define B30(tt) (macroDragBit30?((tt)&0x40000000):0)
+// what monster did I just create here?
+#define B30(tt) (macroDragBit30?((((tt)&0xc0000000)==0x40000000 || ((tt)&0xc0000000)==0x80000000)?0x40000000:0):0)
 
 #define MACRO_DRAG(t) \
   if (macroDragBitMode) { \
@@ -1808,25 +1814,25 @@ void FurnaceGUI::showError(String what) {
       } \
       if (macroDragMouseMoved) { \
         if ((int)round(x-macroDragLineInitial.x)==0) { \
-          t[x]=B30(t[x])|(int)(macroDragLineInitial.y); \
+          t[x]=B30(t[x])^(int)(macroDragLineInitial.y); \
         } else { \
           if ((int)round(x-macroDragLineInitial.x)<0) { \
             for (int i=0; i<=(int)round(macroDragLineInitial.x-x); i++) { \
               int index=(int)round(x+i); \
               if (index<0) continue; \
-              t[index]=B30(t[index])|(int)(y+(macroDragLineInitial.y-y)*((float)i/(float)(macroDragLineInitial.x-x))); \
+              t[index]=B30(t[index])^(int)(y+(macroDragLineInitial.y-y)*((float)i/(float)(macroDragLineInitial.x-x))); \
             } \
           } else { \
             for (int i=0; i<=(int)round(x-macroDragLineInitial.x); i++) { \
               int index=(int)round(i+macroDragLineInitial.x); \
               if (index<0) continue; \
-              t[index]=B30(t[index])|(int)(macroDragLineInitial.y+(y-macroDragLineInitial.y)*((float)i/(x-macroDragLineInitial.x))); \
+              t[index]=B30(t[index])^(int)(macroDragLineInitial.y+(y-macroDragLineInitial.y)*((float)i/(x-macroDragLineInitial.x))); \
             } \
           } \
         } \
       } \
     } else { \
-      t[x]=B30(t[x])|(y); \
+      t[x]=B30(t[x])^(y); \
     } \
   }
 
diff --git a/src/gui/insEdit.cpp b/src/gui/insEdit.cpp
index ea0717154..2a2c8ecd5 100644
--- a/src/gui/insEdit.cpp
+++ b/src/gui/insEdit.cpp
@@ -1197,6 +1197,16 @@ String genericGuide(float value) {
   return fmt::sprintf("%d",(int)value);
 }
 
+inline int deBit30(const int val) {
+  if ((val&0xc0000000)==0x40000000 || (val&0xc0000000)==0x80000000) return val^0x40000000;
+  return val;
+}
+
+inline bool enBit30(const int val) {
+  if ((val&0xc0000000)==0x40000000 || (val&0xc0000000)==0x80000000) return true;
+  return false;
+}
+
 void FurnaceGUI::drawMacros(std::vector<FurnaceGUIMacroDesc>& macros) {
   float asFloat[256];
   int asInt[256];
@@ -1292,9 +1302,9 @@ void FurnaceGUI::drawMacros(std::vector<FurnaceGUIMacroDesc>& macros) {
           asFloat[j]=0;
           asInt[j]=0;
         } else {
-          asFloat[j]=i.macro->val[j+macroDragScroll]&(i.bit30?(~0x40000000):0xffffffff);
-          asInt[j]=(i.macro->val[j+macroDragScroll]&(i.bit30?(~0x40000000):0xffffffff))+i.bitOffset;
-          if (i.bit30) bit30Indicator[j]=(i.macro->val[j+macroDragScroll]&0x40000000)?1:0;
+          asFloat[j]=deBit30(i.macro->val[j+macroDragScroll]);
+          asInt[j]=deBit30(i.macro->val[j+macroDragScroll])+i.bitOffset;
+          if (i.bit30) bit30Indicator[j]=enBit30(i.macro->val[j+macroDragScroll]);
         }
         if (j+macroDragScroll>=i.macro->len || (j+macroDragScroll>i.macro->rel && i.macro->loop<i.macro->rel)) {
           loopIndicator[j]=0;
@@ -1461,10 +1471,10 @@ void FurnaceGUI::drawMacros(std::vector<FurnaceGUIMacroDesc>& macros) {
         ImGui::SetNextItemWidth(availableWidth);
         String& mmlStr=mmlString[index];
         if (ImGui::InputText("##IMacroMML",&mmlStr)) {
-          decodeMMLStr(mmlStr,i.macro->val,i.macro->len,i.macro->loop,i.min,(i.isBitfield)?((1<<(i.isBitfield?i.max:0))-1):i.max,i.macro->rel);
+          decodeMMLStr(mmlStr,i.macro->val,i.macro->len,i.macro->loop,i.min,(i.isBitfield)?((1<<(i.isBitfield?i.max:0))-1):i.max,i.macro->rel,i.bit30);
         }
         if (!ImGui::IsItemActive()) {
-          encodeMMLStr(mmlStr,i.macro->val,i.macro->len,i.macro->loop,i.macro->rel);
+          encodeMMLStr(mmlStr,i.macro->val,i.macro->len,i.macro->loop,i.macro->rel,false,i.bit30);
         }
       }
       ImGui::PopStyleVar();