diff --git a/mk/os-GNU.mk b/mk/os-GNU.mk
index 1fbc1474..d5c4172f 100644
--- a/mk/os-GNU.mk
+++ b/mk/os-GNU.mk
@@ -11,5 +11,5 @@
 SFX=		.GNU.in
 PKG_PREFIX?=	/usr
 
-CPPFLAGS+=	-D_BSD_SOURCE -D_XOPEN_SOURCE=700 -DMAXPATHLEN=4096 -DPATH_MAX=4096
+CPPFLAGS+=	-D_DEFAULT_SOURCE -D_XOPEN_SOURCE=700 -DMAXPATHLEN=4096 -DPATH_MAX=4096
 LIBDL=		-Wl,-Bdynamic -ldl