BauSystem_Main/src/de/steamwar/bausystem/world/Region.java

@@ -198,7 +198,8 @@ public class Region {
     }
 
     public void protect(Schematic schem) throws IOException, NoClipboardException {
-        prototype.protect(this, schem);
+        initSessions();
+        undosessions.push(prototype.protect(this, schem));
     }
 
     public boolean hasExtensionAreaRegistered() {