diff --git a/src/proto/gui_photon.pro b/src/proto/gui_photon.pro
index af33ef5..f6bb50e 100644
--- a/src/proto/gui_photon.pro
+++ b/src/proto/gui_photon.pro
@@ -30,6 +30,7 @@
 guicolor_T gui_mch_get_color __ARGS((char_u *name));
 void gui_mch_set_fg_color __ARGS((guicolor_T color));
 void gui_mch_set_bg_color __ARGS((guicolor_T color));
+void gui_mch_set_sp_color __ARGS((guicolor_T color));
 void gui_mch_invert_rectangle __ARGS((int row, int col, int nr, int nc));
 void gui_mch_clear_block __ARGS((int row1, int col1, int row2, int col2));
 void gui_mch_clear_all __ARGS((void));