diff --git a/app/src/processing/app/Editor.java b/app/src/processing/app/Editor.java
index 34e1515c9..c0ae487f9 100644
--- a/app/src/processing/app/Editor.java
+++ b/app/src/processing/app/Editor.java
@@ -1697,6 +1697,7 @@ public class Editor extends JFrame implements RunnerListener {
 
           } else if (undo != null) {
             undo.addEdit(new CaretAwareUndoableEdit(e.getEdit(), textarea));
+            sketch.setModified(true);
             undoAction.updateUndoState();
             redoAction.updateRedoState();
           }