diff --git a/mock/LightDMMock.js b/mock/LightDMMock.js
index 96159a6..e2abc7b 100644
--- a/mock/LightDMMock.js
+++ b/mock/LightDMMock.js
@@ -11,7 +11,10 @@
  *   Include the file in your theme that needs mocking
  *     <script type="text/javascript" src="mock/LightDMMock.js"></script>
  *   Create a new instance of LightDMMock
- *     var lightdm = lightdm || new LightDMMock(autofill, timeout, autoGuest);
+ *     if(!("lightdm" in window)) {
+ *         var LightDMMock = LightDMMock || {};
+ *         window.lightdm = new LightDMMock(autofill, timeout, autoGuest);
+ *     }
  *
  * @param {boolean} autofill  [wether or not the arrays for users, languages,
  *                             layouts, and sessions need to be filled with mock
diff --git a/readme.md b/readme.md
index 884801b..7735a77 100644
--- a/readme.md
+++ b/readme.md
@@ -12,7 +12,10 @@ git clone git@github.com:CytoDev/LightDMMock.git
 ````
  3. Create a new instance of LightDMMock
 ````javascript
-var lightdm = lightdm || new LightDMMock(autofill, timeout, autoGuest);
+if(!("lightdm" in window)) {
+    var LightDMMock = LightDMMock || {};
+    window.lightdm = new LightDMMock(autofill, timeout, autoGuest);
+}
 ````
 
 ##Parameters of LightDMMock()