diff --git a/src/os_mswin.c b/src/os_mswin.c
index 1c987c2..8000953 100644
--- a/src/os_mswin.c
+++ b/src/os_mswin.c
@@ -553,7 +553,7 @@
 
 #if (defined(FEAT_GUI_MSWIN) && !defined(VIMDLL)) || defined(PROTO)
     void
-mch_settmode(int tmode UNUSED)
+mch_settmode(tmode_T tmode UNUSED)
 {
     // nothing to do
 }