diff --git a/libc/include/sys/fsuid.h b/libc/include/sys/fsuid.h
index e4d9ebc..bb7a58d 100644
--- a/libc/include/sys/fsuid.h
+++ b/libc/include/sys/fsuid.h
@@ -34,9 +34,9 @@
 
 __BEGIN_DECLS
 
-int setfsuid(uid_t) __INTRODUCED_IN(21);
-int setfsgid(gid_t) __INTRODUCED_IN(21);
+int setfsuid(uid_t __uid) __INTRODUCED_IN(21);
+int setfsgid(gid_t __gid) __INTRODUCED_IN(21);
 
 __END_DECLS
 
-#endif /* _SYS_FSUID_H_ */
+#endif