diff --git a/boot/libs.ml b/boot/libs.ml
index 6faacb217ec..b6aeed5a6d5 100644
--- a/boot/libs.ml
+++ b/boot/libs.ml
@@ -1,4 +1,4 @@
-let external_libraries = [ "unix"; "threads" ]
+let external_libraries = [ "threads.posix" ]
 
 let local_libraries =
   [ ("otherlibs/ordering", Some "Ordering", false, None)