diff --git a/src/proto/os_win32.pro b/src/proto/os_win32.pro
index e6fce88..7cdd156 100644
--- a/src/proto/os_win32.pro
+++ b/src/proto/os_win32.pro
@@ -22,6 +22,7 @@
 int mch_ishidden __ARGS((char_u *name));
 int mch_isdir __ARGS((char_u *name));
 int mch_mkdir __ARGS((char_u *name));
+int mch_rmdir __ARGS((char_u *name));
 int mch_is_hard_link __ARGS((char_u *fname));
 int mch_is_symbolic_link __ARGS((char_u *fname));
 int mch_is_linked __ARGS((char_u *fname));