diff --git a/test/1_stdlib/Dispatch.swift b/test/1_stdlib/Dispatch.swift
index 8b9b8e94fdbb5..025420d1468a1 100644
--- a/test/1_stdlib/Dispatch.swift
+++ b/test/1_stdlib/Dispatch.swift
@@ -3,6 +3,9 @@
 
 // REQUIRES: objc_interop
 
+// rdar://27226313
+// REQUIRES: optimized_stdlib
+
 import Dispatch
 import Foundation
 import StdlibUnittest