--- gavl-1.4.0/src/fill_test.c.orig	2023-12-19 07:42:05.584796100 +0100
+++ gavl-1.4.0/src/fill_test.c	2023-12-19 07:42:14.353473100 +0100
@@ -23,6 +23,7 @@
 //#include "colorspace.h" // Common routines
 #include <stdio.h>
 #include <png.h>
+#include <string.h>
 
 static void
 write_png(char * filename, gavl_video_format_t * format, gavl_video_frame_t * frame)
