diff --git a/tests/php/ORM/HierarchyTest.php b/tests/php/ORM/HierarchyTest.php
index 01a1f7f4e5a..202c3ced250 100644
--- a/tests/php/ORM/HierarchyTest.php
+++ b/tests/php/ORM/HierarchyTest.php
@@ -690,6 +690,12 @@ public function testDefaultParent(string $class, ?string $defaultParentConfig, ?
      */
     public function testGetTreeTitleExtension()
     {
+        // Ensure no other extensions are applied which would change the expected result
+        foreach (Group::get_extensions() as $extension) {
+            if ($extension !== 'SilverStripe\ORM\Hierarchy\Hierarchy') {
+                Group::remove_extension($extension);
+            }
+        }
         Group::add_extension(TestTreeTitleExtension::class);
         $group = new Group();
         $group->Title = '<b>My group</b>';