diff --git a/src/os_win32.c b/src/os_win32.c
index d77e216..edd5cda 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -3600,7 +3600,7 @@
  * set the tty in (raw) ? "raw" : "cooked" mode
  */
     void
-mch_settmode(int tmode)
+mch_settmode(tmode_T tmode)
 {
     DWORD cmodein;
     DWORD cmodeout;