diff --git a/lib/libc/sys/Makefile.inc b/lib/libc/sys/Makefile.inc
--- a/lib/libc/sys/Makefile.inc
+++ b/lib/libc/sys/Makefile.inc
@@ -49,7 +49,7 @@
 SRCS+= pipe.c
 SRCS+= shm_open.c
 SRCS+= vadvise.c
-SRCS+= _Fork.c
+SRCS+= POSIX2x_Fork.c
 
 SRCS+=	compat-stub.c
 
diff --git a/lib/libc/sys/_Fork.c b/lib/libc/sys/POSIX2x_Fork.c
rename from lib/libc/sys/_Fork.c
rename to lib/libc/sys/POSIX2x_Fork.c