diff --git a/stdlib/public/BackDeployConcurrency/CMakeLists.txt b/stdlib/public/BackDeployConcurrency/CMakeLists.txt
index 3c734a404e698..646f968c0654a 100644
--- a/stdlib/public/BackDeployConcurrency/CMakeLists.txt
+++ b/stdlib/public/BackDeployConcurrency/CMakeLists.txt
@@ -66,3 +66,4 @@ set(LLVM_OPTIONAL_SOURCES
   TaskSleepDuration.swift)
 
 add_subdirectory(../Concurrency stdlib/public/BackDeployConcurrency)
+add_subdirectory(../Threading stdlib/public/BackDeployConcurrency)