diff --git a/addons/mail/static/tests/chatter_tests.js b/addons/mail/static/tests/chatter_tests.js
index e247c01430a..16bc619e8c7 100644
--- a/addons/mail/static/tests/chatter_tests.js
+++ b/addons/mail/static/tests/chatter_tests.js
@@ -370,7 +370,7 @@ QUnit.test('chatter: post, receive and star messages', function (assert) {
     var done = assert.async();
     assert.expect(28);
     
-    testUtils.patchWindowGetSelection();
+    var unpatchWindowGetSelection = testUtils.patchWindowGetSelection();
 
     var bus = new Bus();
     var BusService = createBusService(bus);
@@ -538,8 +538,7 @@ QUnit.test('chatter: post, receive and star messages', function (assert) {
 
             //cleanup
             form.destroy();
-            testUtils.unpatchWindowGetSelection();
-            
+            unpatchWindowGetSelection();
             done();
         });
 });
diff --git a/addons/mail/static/tests/discuss_tests.js b/addons/mail/static/tests/discuss_tests.js
index 348a6357b5d..550b7d46b72 100644
--- a/addons/mail/static/tests/discuss_tests.js
+++ b/addons/mail/static/tests/discuss_tests.js
@@ -12,7 +12,6 @@ var BasicComposer = Composers.BasicComposer;
 var createBusService = mailTestUtils.createBusService;
 var createDiscuss = mailTestUtils.createDiscuss;
 var patchWindowGetSelection = testUtils.patchWindowGetSelection;
-var unpatchWindowGetSelection = testUtils.unpatchWindowGetSelection;
 
 QUnit.module('mail', {}, function () {
 
@@ -113,7 +112,7 @@ QUnit.test('@ mention in channel', function (assert) {
         // Note: focus is needed in order to trigger rpc 'channel_fetch_listeners'
         $input.focus();
         $input.text("@");
-        patchWindowGetSelection();
+        var unpatchWindowGetSelection = patchWindowGetSelection();
         $input.trigger('keyup');
 
         fetchListenersDef
diff --git a/addons/web/static/tests/helpers/test_utils.js b/addons/web/static/tests/helpers/test_utils.js
index 6f3b3ef4549..5b2fdf2e7f6 100644
--- a/addons/web/static/tests/helpers/test_utils.js
+++ b/addons/web/static/tests/helpers/test_utils.js
@@ -23,8 +23,6 @@ var Widget = require('web.Widget');
 
 var DebouncedField = basic_fields.DebouncedField;
 
-var originalWindowGetSelection; // cached replaced originalGetSelection
-
 /**
  * intercepts an event bubbling up the widget hierarchy. The event intercepted
  * must be a "custom event", i.e. an event generated by the method 'trigger_up'.
@@ -734,21 +732,22 @@ function patch (target, props) {
  * 
  * usage:
  *     QUnit.test('...',function(done){
- *          testUtils.patchWindowGetSelection();
+ *          var unpatchWindowGetSelection = testUtils.patchWindowGetSelection();
  *          
  *          // do something that needs to use window.getSelection()
  *          assert.strictEqual(....);
  *          
  *          // restore the original function
- *          testUtils.unpatchWindowGetSelection();
+ *          unpatchWindowGetSelection();
  *      
  *          // finish the test
  *          done();
  *     })
+ *
+ * @returns {function} the unpatch function
  */
-
 function patchWindowGetSelection() {
-    originalWindowGetSelection = window.getSelection;
+    var originalWindowGetSelection = window.getSelection;
     window.getSelection = function () {
         return {
             removeAllRanges: function () {},
@@ -769,6 +768,9 @@ function patchWindowGetSelection() {
             },
         };
     };
+    return function () {
+        window.getSelection = originalWindowGetSelection;
+    };
 }
 
 /**
@@ -795,14 +797,6 @@ function unpatch(target) {
     delete target.__patchID;
 }
 
-/**
- * after using patchWindowGetSelection, at the end of your test
- * you must restore the default function so there is no impact to the other tests
- */
-function unpatchWindowGetSelection() {
-    window.getSelection = originalWindowGetSelection;
-}
-
 // Loading static files cannot be properly simulated when their real content is
 // really needed. This is the case for static XML files so we load them here,
 // before starting the qunit test suite.
@@ -835,7 +829,6 @@ return $.when(
         triggerMouseEvent: triggerMouseEvent,
         triggerPositionalMouseEvent: triggerPositionalMouseEvent,
         unpatch: unpatch,
-        unpatchWindowGetSelection: unpatchWindowGetSelection,
     };
 });