diff --git a/libc/include/sys/msg.h b/libc/include/sys/msg.h
index e19452c..ad481a0 100644
--- a/libc/include/sys/msg.h
+++ b/libc/include/sys/msg.h
@@ -46,12 +46,12 @@
 typedef __kernel_ulong_t msglen_t;
 
 /** Not useful on Android; disallowed by SELinux. */
-int msgctl(int __msg_id, int __cmd, struct msqid_ds* __buf) __INTRODUCED_IN(26);
+int msgctl(int __msg_id, int __cmd, struct msqid_ds* _Nullable __buf) __INTRODUCED_IN(26);
 /** Not useful on Android; disallowed by SELinux. */
 int msgget(key_t __key, int __flags) __INTRODUCED_IN(26);
 /** Not useful on Android; disallowed by SELinux. */
-ssize_t msgrcv(int __msg_id, void* __msgbuf_ptr, size_t __size, long __type, int __flags) __INTRODUCED_IN(26);
+ssize_t msgrcv(int __msg_id, void* _Nonnull __msgbuf_ptr, size_t __size, long __type, int __flags) __INTRODUCED_IN(26);
 /** Not useful on Android; disallowed by SELinux. */
-int msgsnd(int __msg_id, const void* __msgbuf_ptr, size_t __size, int __flags) __INTRODUCED_IN(26);
+int msgsnd(int __msg_id, const void* _Nonnull __msgbuf_ptr, size_t __size, int __flags) __INTRODUCED_IN(26);
 
 __END_DECLS