diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 31844258d..1a3f84bb2 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -388,6 +388,7 @@ void FurnaceGUI::decodeMMLStr(String& source, int* macro, unsigned char& macroLe
     setBit30=false;
     macroLen++;
     buf=0;
+    MARK_MODIFIED;
   }
 }