--- alevt-1.6.2.orig/exp-gfx.c
+++ alevt-1.6.2/exp-gfx.c
@@ -157,6 +157,7 @@
 
 #ifdef WITH_PNG
 
+#include <zlib.h>
 #include <png.h>
 static int png_open(struct export *e);
 static int png_option(struct export *e, int opt, char *arg);