diff --git a/src/strings_func.h b/src/strings_func.h
--- a/src/strings_func.h
+++ b/src/strings_func.h
@@ -277,7 +277,7 @@ public:
 	 */
 	virtual void SetFontNames(struct FreeTypeSettings *settings, const char *font_name, const void *os_data = nullptr) = 0;
 
-	bool FindMissingGlyphs(const char **str);
+	bool FindMissingGlyphs();
 };
 
 void CheckForMissingGlyphs(bool base_font = true, MissingGlyphSearcher *search = nullptr);