diff --git a/src/gui/doAction.cpp b/src/gui/doAction.cpp
index 77fc7b7f7..3acc4bc59 100644
--- a/src/gui/doAction.cpp
+++ b/src/gui/doAction.cpp
@@ -751,6 +751,9 @@ void FurnaceGUI::doAction(int what) {
         wantScrollList=true;
         e->song.wave[curWave]->len=finalWidth;
         e->song.wave[curWave]->max=finalHeight-1;
+        for (int j=0; j<finalWidth; j++) {
+          e->song.wave[curWave]->data[j]=(j*finalHeight)/finalWidth;
+        }
         MARK_MODIFIED;
         RESET_WAVE_MACRO_ZOOM;
       }
diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 79dba811c..0f12eff68 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -5977,6 +5977,9 @@ bool FurnaceGUI::loop() {
           } else {
             e->song.wave[curWave]->len=i.width;
             e->song.wave[curWave]->max=i.height-1;
+            for (int j=0; j<i.width; j++) {
+              e->song.wave[curWave]->data[j]=(j*i.height)/i.width;
+            }
             MARK_MODIFIED;
             RESET_WAVE_MACRO_ZOOM;
           }