diff --git a/libc/include/sys/msg.h b/libc/include/sys/msg.h
index 0273499..e19452c 100644
--- a/libc/include/sys/msg.h
+++ b/libc/include/sys/msg.h
@@ -26,8 +26,12 @@
  * SUCH DAMAGE.
  */
 
-#ifndef _SYS_MSG_H_
-#define _SYS_MSG_H_
+#pragma once
+
+/**
+ * @file sys/msg.h
+ * @brief System V message queues. Not useful on Android because it's disallowed by SELinux.
+ */
 
 #include <sys/cdefs.h>
 #include <sys/ipc.h>
@@ -41,11 +45,13 @@
 typedef __kernel_ulong_t msgqnum_t;
 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);
+/** 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);
+/** Not useful on Android; disallowed by SELinux. */
 int msgsnd(int __msg_id, const void* __msgbuf_ptr, size_t __size, int __flags) __INTRODUCED_IN(26);
 
 __END_DECLS
-
-#endif