diff --git a/src/proto/gui_w32.pro b/src/proto/gui_w32.pro
index 6756dc8..4ead92e 100644
--- a/src/proto/gui_w32.pro
+++ b/src/proto/gui_w32.pro
@@ -61,6 +61,7 @@
 char_u *gui_mch_browse(int saving, char_u *title, char_u *dflt, char_u *ext, char_u *initdir, char_u *filter);
 char_u *gui_mch_browsedir(char_u *title, char_u *initdir);
 void gui_mch_set_parent(char *title);
+char *gui_mch_do_spawn(char_u *arg);
 void gui_mch_prepare(int *argc, char **argv);
 int gui_mch_init(void);
 void gui_mch_set_shellsize(int width, int height, int min_width, int min_height, int base_width, int base_height, int direction);