diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 8ea22a144..0d53e97da 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -1783,7 +1783,31 @@ void FurnaceGUI::showError(String what) {
 #define B30(tt) (macroDragBit30?((((tt)&0xc0000000)==0x40000000 || ((tt)&0xc0000000)==0x80000000)?0x40000000:0):0)
 
 #define MACRO_DRAG(t) \
-  if (macroDragBitMode) { \
+  if (macroDragSettingBit30) { \
+    if (macroDragLastX!=x || macroDragLastY!=y) { \
+      macroDragLastX=x; \
+      macroDragLastY=y; \
+      if (macroDragInitialValueSet) { \
+        if (!macroDragInitialValue) { \
+          if (t[x]&0x80000000) { \
+            t[x]&=~0x40000000; \
+          } else { \
+            t[x]|=0x40000000; \
+          } \
+        } else { \
+          if (t[x]&0x80000000) { \
+            t[x]|=0x40000000; \
+          } else { \
+            t[x]&=~0x40000000; \
+          } \
+        } \
+      } else { \
+        macroDragInitialValue=(((t[x])&0xc0000000)==0x40000000 || ((t[x])&0xc0000000)==0x80000000); \
+        macroDragInitialValueSet=true; \
+        t[x]^=0x40000000; \
+      } \
+    } \
+  } else if (macroDragBitMode) { \
     if (macroDragLastX!=x || macroDragLastY!=y) { \
       macroDragLastX=x; \
       macroDragLastY=y; \
@@ -4893,6 +4917,7 @@ FurnaceGUI::FurnaceGUI():
   macroDragInitialValue(false),
   macroDragChar(false),
   macroDragBit30(false),
+  macroDragSettingBit30(false),
   macroDragLineMode(false),
   macroDragMouseMoved(false),
   macroDragLineInitial(0,0),
diff --git a/src/gui/gui.h b/src/gui/gui.h
index a7f906aea..80aa087ff 100644
--- a/src/gui/gui.h
+++ b/src/gui/gui.h
@@ -1397,6 +1397,7 @@ class FurnaceGUI {
   bool macroDragInitialValue;
   bool macroDragChar;
   bool macroDragBit30;
+  bool macroDragSettingBit30;
   bool macroDragLineMode;
   bool macroDragMouseMoved;
   ImVec2 macroDragLineInitial;
diff --git a/src/gui/insEdit.cpp b/src/gui/insEdit.cpp
index 2a2c8ecd5..c89652a37 100644
--- a/src/gui/insEdit.cpp
+++ b/src/gui/insEdit.cpp
@@ -1374,6 +1374,7 @@ void FurnaceGUI::drawMacros(std::vector<FurnaceGUIMacroDesc>& macros) {
         macroDragLen=totalFit;
         macroDragActive=true;
         macroDragBit30=i.bit30;
+        macroDragSettingBit30=false;
         macroDragTarget=i.macro->val;
         macroDragChar=false;
         macroDragLineMode=(i.isBitfield)?false:ImGui::IsItemClicked(ImGuiMouseButton_Right);
@@ -1442,9 +1443,24 @@ void FurnaceGUI::drawMacros(std::vector<FurnaceGUIMacroDesc>& macros) {
         }
 
         // bit 30 area
-        // TODO: ability to set it
         if (i.bit30) {
           PlotCustom("##IMacroBit30",bit30Indicator,totalFit,macroDragScroll,NULL,0,1,ImVec2(availableWidth,12.0f*dpiScale),sizeof(float),i.color,i.macro->len-macroDragScroll,&macroHoverBit30);
+          if (ImGui::IsItemClicked(ImGuiMouseButton_Left)) {
+            macroDragStart=ImGui::GetItemRectMin();
+            macroDragAreaSize=ImVec2(availableWidth,12.0f*dpiScale);
+            macroDragInitialValueSet=false;
+            macroDragInitialValue=false;
+            macroDragLen=totalFit;
+            macroDragActive=true;
+            macroDragBit30=i.bit30;
+            macroDragSettingBit30=true;
+            macroDragTarget=i.macro->val;
+            macroDragChar=false;
+            macroDragLineMode=false;
+            macroDragLineInitial=ImVec2(0,0);
+            lastMacroDesc=i;
+            processDrags(ImGui::GetMousePos().x,ImGui::GetMousePos().y);
+          }
         }
 
         // loop area