diff --git a/7.4.921 b/7.4.921
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+To: vim_dev@googlegroups.com
+Subject: Patch 7.4.921
+Fcc: outbox
+From: Bram Moolenaar <Bram@moolenaar.net>
+Mime-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+------------
+
+Patch 7.4.921 (after 7.4.906)
+Problem:    Missing proto file update. (Randall W. Morris)
+Solution:   Add the missing line for mch_ishidden.
+Files:      src/proto/os_win32.pro
+
+
+*** ../vim-7.4.920/src/proto/os_win32.pro	2015-03-21 17:32:14.066779916 +0100
+--- src/proto/os_win32.pro	2015-11-02 14:32:36.076850843 +0100
+***************
+*** 19,24 ****
+--- 19,25 ----
+  long mch_getperm __ARGS((char_u *name));
+  int mch_setperm __ARGS((char_u *name, long perm));
+  void mch_hide __ARGS((char_u *name));
++ int mch_ishidden __ARGS((char_u *name));
+  int mch_isdir __ARGS((char_u *name));
+  int mch_mkdir __ARGS((char_u *name));
+  int mch_is_hard_link __ARGS((char_u *fname));
+*** ../vim-7.4.920/src/version.c	2015-11-10 20:45:05.437451313 +0100
+--- src/version.c	2015-11-10 20:51:19.789698207 +0100
+***************
+*** 743,744 ****
+--- 743,746 ----
+  {   /* Add new patch number below this line */
++ /**/
++     921,
+  /**/
+
+-- 
+A fool learns from his mistakes, a wise man from someone else's.
+
+ /// Bram Moolenaar -- Bram@Moolenaar.net -- http://www.Moolenaar.net   \\\
+///        sponsor Vim, vote for features -- http://www.Vim.org/sponsor/ \\\
+\\\  an exciting new programming language -- http://www.Zimbu.org        ///
+ \\\            help me help AIDS victims -- http://ICCF-Holland.org    ///