diff --git a/test/t/struct.rb b/test/t/struct.rb
index 5e86c70bf..fff02ee56 100644
--- a/test/t/struct.rb
+++ b/test/t/struct.rb
@@ -1,7 +1,7 @@
 ##
 # Struct ISO Test
 
-if StructEnabled
+if Object.const_defined?(:Struct)
   assert('Struct', '15.2.18') do
     Struct.class == Class
   end