--- mng.c.orig	Fri Apr 28 11:52:25 2017
+++ mng.c	Fri Apr 28 11:53:19 2017
@@ -43,6 +43,8 @@ typedef struct {
 	mng_uint32	delay;     /* ticks to wait before resuming decode */
 } mngstuff;
 
+void mng_window_setup(mngstuff *, int, int, int, int);
+
 /* callbacks for the mng decoder */
 
 /* memory allocation; data must be zeroed */