diff --git a/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/physical/ByteArrayImageLayout.java b/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/physical/ByteArrayImageLayout.java
index cdc7898..6ff48df 100644
--- a/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/physical/ByteArrayImageLayout.java
+++ b/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/physical/ByteArrayImageLayout.java
@@ -41,6 +41,7 @@ public class ByteArrayImageLayout {
 	 */
 	public ByteArrayImageLayout(byte[] diskImage) {
 		setDiskImage(diskImage);
+		changed = false;	// setDiskImage by default sets to true but we don't want that
 	}
 
 	/**
diff --git a/lib/ac-swt-common/src/main/java/com/webcodepro/applecommander/ui/swt/DiskWindow.java b/lib/ac-swt-common/src/main/java/com/webcodepro/applecommander/ui/swt/DiskWindow.java
index 2af894a..9f1fb89 100644
--- a/lib/ac-swt-common/src/main/java/com/webcodepro/applecommander/ui/swt/DiskWindow.java
+++ b/lib/ac-swt-common/src/main/java/com/webcodepro/applecommander/ui/swt/DiskWindow.java
@@ -19,6 +19,7 @@
  */
 package com.webcodepro.applecommander.ui.swt;
 
+import com.webcodepro.applecommander.ui.swt.util.SwtUtil;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.custom.CTabFolder;
 import org.eclipse.swt.events.DisposeEvent;
@@ -74,6 +75,13 @@ public class DiskWindow {
 					dispose(event);
 				}
 			});
+		shell.addListener(SWT.Close, (event) -> {
+			if (disks[0].hasChanged()) {
+				int button = SwtUtil.showYesNoDialog(shell, "Are you sure?",
+						"The disk has been modified. Are you certain you want to quit?");
+				event.doit = button == SWT.YES;
+			}
+		});
 			
 		CTabFolder tabFolder = new CTabFolder(shell, SWT.BOTTOM);
 		new DiskExplorerTab(tabFolder, disks, imageManager, this);