diff --git a/src/engine/cmdStream.cpp b/src/engine/cmdStream.cpp
index 9f6b75a37..475761608 100644
--- a/src/engine/cmdStream.cpp
+++ b/src/engine/cmdStream.cpp
@@ -169,7 +169,7 @@ bool DivCSPlayer::tick() {
           chan[i].volSpeedTarget=-1;
           break;
         case 0xc9: // porta
-          chan[i].portaTarget=(signed char)stream.readC();
+          chan[i].portaTarget=(int)((unsigned char)stream.readC())-60;
           chan[i].portaSpeed=(unsigned char)stream.readC();
           break;
         case 0xca: { // legato
diff --git a/src/engine/cmdStreamOps.cpp b/src/engine/cmdStreamOps.cpp
index c07315421..3c1439b15 100644
--- a/src/engine/cmdStreamOps.cpp
+++ b/src/engine/cmdStreamOps.cpp
@@ -378,10 +378,15 @@ void writeCommandValues(SafeWriter* w, const DivCommand& c, bool bigEndian) {
       w->writeC(c.value);
       break;
     case DIV_CMD_HINT_PANNING:
-    case DIV_CMD_HINT_PORTA:
       w->writeC(c.value);
       w->writeC(c.value2);
       break;
+    case DIV_CMD_HINT_PORTA: {
+      unsigned char val=CLAMP(c.value+60,0,255);
+      w->writeC(val);
+      w->writeC(c.value2);
+      break;
+    }
     case DIV_CMD_PRE_PORTA:
       w->writeC((c.value?0x80:0)|(c.value2?0x40:0));
       break;