diff --git a/test/dl/test_dl2.rb b/test/dl/test_dl2.rb
index 7b47fc8024..5d3af94b3d 100644
--- a/test/dl/test_dl2.rb
+++ b/test/dl/test_dl2.rb
@@ -1,5 +1,6 @@
 require_relative 'test_base.rb'
 require 'dl/callback'
+require 'dl/func'
 
 module DL
 class TestDL < TestBase