diff --git a/src/textfile_gui.h b/src/textfile_gui.h
--- a/src/textfile_gui.h
+++ b/src/textfile_gui.h
@@ -43,7 +43,7 @@ struct TextfileWindow : public Window, M
 	FontSize DefaultSize() override;
 	const char *NextString() override;
 	bool Monospace() override;
-	void SetFontNames(FreeTypeSettings *settings, const char *font_name) override;
+	void SetFontNames(FreeTypeSettings *settings, const char *font_name, const void *os_data) override;
 
 	virtual void LoadTextfile(const char *textfile, Subdirectory dir);