diff --git a/activerecord/test/cases/serialized_attribute_test.rb b/activerecord/test/cases/serialized_attribute_test.rb
index 08ab4dc600..f6cd4f85ee 100644
--- a/activerecord/test/cases/serialized_attribute_test.rb
+++ b/activerecord/test/cases/serialized_attribute_test.rb
@@ -371,7 +371,7 @@ class SerializedAttributeTest < ActiveRecord::TestCase
   end
 
   def test_serialized_attribute_works_under_concurrent_initial_access
-    model = Topic.dup
+    model = ::Topic.dup
 
     topic = model.last
     topic.update group: "1"