diff --git a/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js b/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js
index 5395386087..1fc03c6232 100644
--- a/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js
+++ b/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js
@@ -58,9 +58,9 @@
             elem.value = chosenId;
         }
         $(elem).trigger('change');
-        const index = window.relatedWindows.indexOf(win);
+        const index = relatedWindows.indexOf(win);
         if (index > -1) {
-            window.relatedWindows.splice(index, 1);
+            relatedWindows.splice(index, 1);
         }
         win.close();
     }
@@ -206,6 +206,7 @@
     window.dismissChangeRelatedObjectPopup = dismissChangeRelatedObjectPopup;
     window.dismissDeleteRelatedObjectPopup = dismissDeleteRelatedObjectPopup;
     window.dismissChildPopups = dismissChildPopups;
+    window.relatedWindows = relatedWindows;
 
     // Kept for backward compatibility
     window.showAddAnotherPopup = showRelatedObjectPopup;
diff --git a/js_tests/admin/RelatedObjectLookups.test.js b/js_tests/admin/RelatedObjectLookups.test.js
index 722aa7ae7b..0d71d88f2a 100644
--- a/js_tests/admin/RelatedObjectLookups.test.js
+++ b/js_tests/admin/RelatedObjectLookups.test.js
@@ -8,7 +8,6 @@ QUnit.module('admin.RelatedObjectLookups', {
             <input type="text" id="test_id" name="test" />
             <input type="text" id="many_test_id" name="many_test" class="vManyToManyRawIdAdminField" />
         `);
-        window.relatedWindows = window.relatedWindows || [];
     }
 });