diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 71f4fecdc..d6e689116 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -2419,7 +2419,7 @@ void FurnaceGUI::processDrags(int dragX, int dragY) {
       if (y>waveDragMax) y=waveDragMax;
       if (y<waveDragMin) y=waveDragMin;
       waveDragTarget[x]=y;
-      e->notifyWaveChange(curWave);
+      notifyWaveChange=true;
       MARK_MODIFIED;
     }
   }
@@ -3746,6 +3746,11 @@ bool FurnaceGUI::loop() {
       midiLock.unlock();
     }
 
+    if (notifyWaveChange) {
+      notifyWaveChange=false;
+      e->notifyWaveChange(curWave);
+    }
+
     eventTimeEnd=SDL_GetPerformanceCounter();
 
     if (SDL_GetWindowFlags(sdlWin)&SDL_WINDOW_MINIMIZED) {
@@ -6718,6 +6723,7 @@ FurnaceGUI::FurnaceGUI():
   preserveChanPos(false),
   wantScrollList(false),
   noteInputPoly(true),
+  notifyWaveChange(false),
   displayPendingIns(false),
   pendingInsSingle(false),
   displayPendingRawSample(false),
diff --git a/src/gui/gui.h b/src/gui/gui.h
index 4e5647515..c87b60a1d 100644
--- a/src/gui/gui.h
+++ b/src/gui/gui.h
@@ -1310,7 +1310,7 @@ class FurnaceGUI {
   bool vgmExportDirectStream, displayInsTypeList;
   bool portrait, injectBackUp, mobileMenuOpen, warnColorPushed;
   bool wantCaptureKeyboard, oldWantCaptureKeyboard, displayMacroMenu;
-  bool displayNew, fullScreen, preserveChanPos, wantScrollList, noteInputPoly;
+  bool displayNew, fullScreen, preserveChanPos, wantScrollList, noteInputPoly, notifyWaveChange;
   bool displayPendingIns, pendingInsSingle, displayPendingRawSample, snesFilterHex, modTableHex, displayEditString;
   bool mobileEdit;
   bool killGraphics;