diff --git a/src/system/libroot/posix/stdlib/Jamfile b/src/system/libroot/posix/stdlib/Jamfile
index e9bdf7fe2d..c84c66a5c4 100644
--- a/src/system/libroot/posix/stdlib/Jamfile
+++ b/src/system/libroot/posix/stdlib/Jamfile
@@ -1,7 +1,7 @@
 SubDir HAIKU_TOP src system libroot posix stdlib ;
 
 UsePrivateHeaders drivers libroot runtime_loader shared ;
-UsePrivateHeaders kernel ;	# for <util/*>
+SubDirCcFlags -D_DEFAULT_SOURCE ;
 
 local architectureObject ;
 for architectureObject in [ MultiArchSubDirSetup ] {