diff --git a/libc/include/sched.h b/libc/include/sched.h
index 6600bae..33b9ad6 100644
--- a/libc/include/sched.h
+++ b/libc/include/sched.h
@@ -69,8 +69,9 @@
 #define CLONE_CHILD_SETTID   0x01000000
 #define CLONE_STOPPED        0x02000000
 
-extern int    clone(int (*fn)(void*), void *child_stack, int flags, void *arg);
-extern pid_t  __clone(int, void *);
+#ifdef __GNU_SOURCE
+extern int clone(int (*fn)(void *), void *child_stack, int flags, void*  arg, ...);
+#endif
 
 __END_DECLS