diff --git a/src/js/.eslintrc.js b/src/js/.eslintrc.js
index f78079f..685c3c9 100644
--- a/src/js/.eslintrc.js
+++ b/src/js/.eslintrc.js
@@ -6,6 +6,7 @@ module.exports = {
     "assignManager": true,
     "badge": true,
     "backgroundLogic": true,
+    "differ": true,
     "identityState": true,
     "messageHandler": true
   }
diff --git a/src/js/background/backgroundLogic.js b/src/js/background/backgroundLogic.js
index 2c63d25..4f55714 100644
--- a/src/js/background/backgroundLogic.js
+++ b/src/js/background/backgroundLogic.js
@@ -280,7 +280,7 @@ const backgroundLogic = {
     const afterIds = Array.from(sortMap.values()).reduce((acc, val) => acc.concat(val), []).map(tab => tab.id);
     const beforeIds = sortedTabs.map(tab => tab.id);
     let sortedIds = beforeIds.slice(0);
-    for (const difference of Diff.diff(beforeIds, afterIds)) {
+    for (const difference of differ.diff(beforeIds, afterIds)) {
       if (!difference.added)
         continue;
       let movingIds = difference.value;
diff --git a/src/js/background/diff.js b/src/js/background/differ.js
similarity index 99%
rename from src/js/background/diff.js
rename to src/js/background/differ.js
index 7d5b511..58a42e4 100644
--- a/src/js/background/diff.js
+++ b/src/js/background/differ.js
@@ -39,7 +39,7 @@ IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISI
 OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-const Diff = {
+const differ = { // eslint-disable-line no-unused-vars
   diff(oldValues, newValues) {
     oldValues = oldValues.slice();
     newValues = newValues.slice();
diff --git a/src/js/background/index.html b/src/js/background/index.html
index da8ff9b..fcb7b7f 100644
--- a/src/js/background/index.html
+++ b/src/js/background/index.html
@@ -11,13 +11,14 @@
       "js/background/badge.js",
       "js/background/identityState.js",
       "js/background/messageHandler.js",
+      "js/background/differ.js",
     ]
 -->
-    <script type="text/javascript" src="diff.js"></script>
     <script type="text/javascript" src="backgroundLogic.js"></script>
     <script type="text/javascript" src="assignManager.js"></script>
     <script type="text/javascript" src="badge.js"></script>
     <script type="text/javascript" src="identityState.js"></script>
     <script type="text/javascript" src="messageHandler.js"></script>
+    <script type="text/javascript" src="differ.js"></script>
   </body>
 </html>