diff --git a/papers/format.md b/papers/format.md
index 5aef984ee..389b6e61e 100644
--- a/papers/format.md
+++ b/papers/format.md
@@ -32,6 +32,7 @@ these fields are 0 in format versions prior to 100 (0.6pre1).
 
 the format versions are:
 
+- 138: Furnace dev138
 - 137: Furnace dev137
 - 136: Furnace dev136
 - 135: Furnace dev135
@@ -399,6 +400,9 @@ size | description
  4?? | patchbay
      | - see next section for more details.
   1  | automatic patchbay (>=136)
+ --- | **a couple more compat flags** (>=138)
+  1  | broken portamento during legato
+  7  | reserved
 ```
 
 # patchbay
diff --git a/src/engine/engine.h b/src/engine/engine.h
index 88e6e6764..75b0ad94c 100644
--- a/src/engine/engine.h
+++ b/src/engine/engine.h
@@ -47,8 +47,8 @@
 #define BUSY_BEGIN_SOFT softLocked=true; isBusy.lock();
 #define BUSY_END isBusy.unlock(); softLocked=false;
 
-#define DIV_VERSION "dev137"
-#define DIV_ENGINE_VERSION 137
+#define DIV_VERSION "dev138"
+#define DIV_ENGINE_VERSION 138
 // for imports
 #define DIV_VERSION_MOD 0xff01
 #define DIV_VERSION_FC 0xff02
diff --git a/src/engine/fileOps.cpp b/src/engine/fileOps.cpp
index 2365da594..c049545aa 100644
--- a/src/engine/fileOps.cpp
+++ b/src/engine/fileOps.cpp
@@ -1716,6 +1716,9 @@ bool DivEngine::loadFur(unsigned char* file, size_t len) {
     if (ds.version<130) {
       ds.oldArpStrategy=true;
     }
+    if (ds.version<138) {
+      ds.brokenPortaLegato=true;
+    }
     ds.isDMF=false;
 
     reader.readS(); // reserved
@@ -2221,6 +2224,13 @@ bool DivEngine::loadFur(unsigned char* file, size_t len) {
 
     if (ds.version>=136) song.patchbayAuto=reader.readC();
 
+    if (ds.version>=138) {
+      ds.brokenPortaArp=reader.readC();
+      for (int i=0; i<7; i++) {
+        reader.readC();
+      }
+    }
+
     // read system flags
     if (ds.version>=119) {
       logD("reading chip flags...");
@@ -4515,6 +4525,12 @@ SafeWriter* DivEngine::saveFur(bool notPrimary) {
   }
   w->writeC(song.patchbayAuto);
 
+  // even more compat flags
+  w->writeC(song.brokenPortaLegato);
+  for (int i=0; i<7; i++) {
+    w->writeC(0);
+  }
+
   blockEndSeek=w->tell();
   w->seek(blockStartSeek,SEEK_SET);
   w->writeI(blockEndSeek-blockStartSeek-4);
diff --git a/src/engine/playback.cpp b/src/engine/playback.cpp
index 33f2d66c7..88a115a33 100644
--- a/src/engine/playback.cpp
+++ b/src/engine/playback.cpp
@@ -896,7 +896,7 @@ void DivEngine::processRow(int i, bool afterDelay) {
       chan[i].vibratoPos=0;
     }
     dispatchCmd(DivCommand(DIV_CMD_PITCH,i,chan[i].pitch+(((chan[i].vibratoDepth*vibTable[chan[i].vibratoPos]*chan[i].vibratoFine)>>4)/15)));
-    if (chan[i].legato) {
+    if (chan[i].legato && (!chan[i].inPorta || song.brokenPortaLegato)) {
       dispatchCmd(DivCommand(DIV_CMD_LEGATO,i,chan[i].note));
       dispatchCmd(DivCommand(DIV_CMD_HINT_LEGATO,i,chan[i].note));
     } else {
diff --git a/src/engine/song.h b/src/engine/song.h
index dfe579bbb..61083c185 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -330,6 +330,7 @@ struct DivSong {
   bool autoSystem;
   bool oldArpStrategy;
   bool patchbayAuto;
+  bool brokenPortaLegato;
 
   std::vector<DivInstrument*> ins;
   std::vector<DivWavetable*> wave;
@@ -439,7 +440,8 @@ struct DivSong {
     disableSampleMacro(false),
     autoSystem(true),
     oldArpStrategy(false),
-    patchbayAuto(true) {
+    patchbayAuto(true),
+    brokenPortaLegato(false) {
     for (int i=0; i<DIV_MAX_CHIPS; i++) {
       system[i]=DIV_SYSTEM_NULL;
       systemVol[i]=1.0;
diff --git a/src/gui/compatFlags.cpp b/src/gui/compatFlags.cpp
index 11c996c20..97913cf31 100644
--- a/src/gui/compatFlags.cpp
+++ b/src/gui/compatFlags.cpp
@@ -293,6 +293,10 @@ void FurnaceGUI::drawCompatFlags() {
     if (ImGui::IsItemHovered()) {
       ImGui::SetTooltip("behavior changed in 0.6pre2");
     }
+    ImGui::Checkbox("Broken portamento during legato",&e->song.brokenPortaLegato);
+    if (ImGui::IsItemHovered()) {
+      ImGui::SetTooltip("behavior changed in 0.6pre4");
+    }
   }
   if (ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows)) curWindow=GUI_WINDOW_COMPAT_FLAGS;
   ImGui::End();