diff --git a/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js b/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js
index 74d17bfc3e..be37fda973 100644
--- a/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js
+++ b/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js
@@ -55,11 +55,11 @@
         if (elem.classList.contains('vManyToManyRawIdAdminField') && elem.value) {
             elem.value += ',' + chosenId;
         } else {
-            document.getElementById(name).value = chosenId;
+            elem.value = chosenId;
         }
-        const index = relatedWindows.indexOf(win);
+        const index = window.relatedWindows.indexOf(win);
         if (index > -1) {
-            relatedWindows.splice(index, 1);
+            window.relatedWindows.splice(index, 1);
         }
         win.close();
     }
diff --git a/js_tests/admin/RelatedObjectLookups.test.js b/js_tests/admin/RelatedObjectLookups.test.js
new file mode 100644
index 0000000000..64433cb623
--- /dev/null
+++ b/js_tests/admin/RelatedObjectLookups.test.js
@@ -0,0 +1,38 @@
+/* global QUnit, RelatedObjectLookups */
+'use strict';
+
+QUnit.module('admin.RelatedObjectLookups', {
+    beforeEach: function() {
+        const $ = django.jQuery;
+        $('#qunit-fixture').append(`
+            <input type="text" id="test_id" name="test" />
+            <input type="text" id="many_test_id" name="many_test" class="vManyToManyRawIdAdminField" />
+        `);
+        window.relatedWindows = window.relatedWindows || [];
+    }
+});
+
+QUnit.test('dismissRelatedLookupPopup closes popup window', function(assert) {
+    const testId = 'test_id';
+    let windowClosed = false;
+    const mockWin = {
+        name: testId,
+        close: function() {
+            windowClosed = true;
+        }
+    };
+    window.dismissRelatedLookupPopup(mockWin, '123');
+    assert.true(windowClosed, 'Popup window should be closed');
+});
+
+QUnit.test('dismissRelatedLookupPopup removes window from relatedWindows array', function(assert) {
+    const testId = 'test_id';
+    const mockWin = {
+        name: testId,
+        close: function() {}
+    };
+    window.relatedWindows.push(mockWin);
+    assert.equal(window.relatedWindows.indexOf(mockWin), 0, 'Window should be in relatedWindows array');
+    window.dismissRelatedLookupPopup(mockWin, '123');
+    assert.equal(window.relatedWindows.indexOf(mockWin), -1, 'Window should be removed from relatedWindows array');
+});
diff --git a/js_tests/tests.html b/js_tests/tests.html
index 011998e5a7..87e347cc0c 100644
--- a/js_tests/tests.html
+++ b/js_tests/tests.html
@@ -125,6 +125,7 @@
     <script src='./admin/navigation.test.js'></script>
 
     <script src='../django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js' data-cover></script>
+    <script src='./admin/RelatedObjectLookups.test.js'></script>
 
     <script src='./admin/DateTimeShortcuts.test.js'></script>
     <script src='../django/contrib/admin/static/admin/js/calendar.js' data-cover></script>