diff --git a/components/rtgui/include/rtgui/font.h b/components/rtgui/include/rtgui/font.h
index a1ec7f644a3c19ebbffb17928f541c6b27532475..177d6a6ec624c1be8eae6a8eab3edd83916f1414 100644
--- a/components/rtgui/include/rtgui/font.h
+++ b/components/rtgui/include/rtgui/font.h
@@ -73,7 +73,7 @@ struct rtgui_hz_file_font
     /* font file name */
     const char* font_fn;
 };
-extern struct rtgui_font_engine rtgui_hz_file_font_engine;
+extern const struct rtgui_font_engine rtgui_hz_file_font_engine;
 
 struct rtgui_font
 {