diff --git a/chapter-03-the-liskov-substitution-principle/dropboxFile.js b/chapter-03-the-liskov-substitution-principle/dropboxFile.js
new file mode 100644
index 0000000..57391ba
--- /dev/null
+++ b/chapter-03-the-liskov-substitution-principle/dropboxFile.js
@@ -0,0 +1,25 @@
+/**
+ * In order to improve the understanding of this code, this file it is supposing to implement the following interface:
+ *
+ * interface FileInterface {
+ *  function rename(name);
+ *  function changeOwner(user, group);
+ * }
+ *
+ * Quack Quack Quack 🦆 typing :D
+ */
+
+function dropboxFile() {
+    function rename(name) {}
+
+    function changeOwner(user, group) {
+        new Error('Not implemented for Dropbox files');
+    }
+
+    return {
+        rename,
+        changeOwner,
+    };
+}
+
+module.exports = dropboxFile;