diff --git a/src/proto/os_win32.pro b/src/proto/os_win32.pro
index a3f5b3e..68d4ee2 100644
--- a/src/proto/os_win32.pro
+++ b/src/proto/os_win32.pro
@@ -20,6 +20,7 @@
 int mch_setperm __ARGS((char_u *name, long perm));
 void mch_hide __ARGS((char_u *name));
 int mch_isdir __ARGS((char_u *name));
+int mch_mkdir __ARGS((char_u *name));
 int mch_is_linked __ARGS((char_u *fname));
 int win32_fileinfo __ARGS((char_u *name, BY_HANDLE_FILE_INFORMATION *lpFileInfo));
 int mch_writable __ARGS((char_u *name));