diff --git a/src/proto/os_win32.pro b/src/proto/os_win32.pro
index 15c1323..d8f9ac3 100644
--- a/src/proto/os_win32.pro
+++ b/src/proto/os_win32.pro
@@ -39,7 +39,7 @@
 vim_acl_T mch_get_acl(char_u *fname);
 void mch_set_acl(char_u *fname, vim_acl_T acl);
 void mch_free_acl(vim_acl_T acl);
-void mch_settmode(int tmode);
+void mch_settmode(tmode_T tmode);
 int mch_get_shellsize(void);
 void mch_set_shellsize(void);
 void mch_new_shellsize(void);