diff --git a/test/webrick/test_httpproxy.rb b/test/webrick/test_httpproxy.rb
index 8149d78..1c2f2fc 100644
--- a/test/webrick/test_httpproxy.rb
+++ b/test/webrick/test_httpproxy.rb
@@ -213,7 +213,7 @@ def test_big_bodies
         end
       end
     end
-  end
+  end if RUBY_VERSION >= '2.5'
 
   def test_http10_proxy_chunked
     # Testing HTTP/1.0 client request and HTTP/1.1 chunked response