diff --git a/src/proto/os_mswin.pro b/src/proto/os_mswin.pro
index 17a9ba2..4731010 100644
--- a/src/proto/os_mswin.pro
+++ b/src/proto/os_mswin.pro
@@ -51,6 +51,7 @@
 char *charset_id2name(int id);
 char *quality_id2name(DWORD id);
 void gui_mch_expand_font(optexpand_T *args, void *param, int (*add_match)(char_u *val));
+UINT WINAPI vimGetDpiForSystem(void);
 int get_logfont(LOGFONTW *lf, char_u *name, HDC printer_dc, int verbose);
 void channel_init_winsock(void);
 /* vim: set ft=c : */