diff --git a/src/proto/gui_x11.pro b/src/proto/gui_x11.pro
index f49f590..3fd4673 100644
--- a/src/proto/gui_x11.pro
+++ b/src/proto/gui_x11.pro
@@ -16,7 +16,7 @@
 int gui_mch_init_font __ARGS((char_u *font_name, int do_fontset));
 GuiFont gui_mch_get_font __ARGS((char_u *name, int giveErrorIfMissing));
 char_u *gui_mch_get_fontname __ARGS((GuiFont font, char_u *name));
-int gui_mch_adjust_charsize __ARGS((void));
+int gui_mch_adjust_charheight __ARGS((void));
 void gui_mch_set_font __ARGS((GuiFont font));
 void gui_mch_set_fontset __ARGS((GuiFontset fontset));
 void gui_mch_free_font __ARGS((GuiFont font));