--- a/src/ref_gl/gl_local.h
+++ b/src/ref_gl/gl_local.h
@@ -29,6 +29,7 @@
 #include <GL/glu.h>
 #include <GL/glext.h>
 
+#include <zlib.h> /* Z_DEFAULT_COMPRESSION */
 #include <png.h>
 #include <jpeglib.h>
 
Subject: [PATCH] Fix build with libpng 1.4.0

From the 1.4.0 release notes:
```
   m. The function png_set_gray_1_2_4_to_8() was removed. It has been
      deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
      png_set_expand_gray_1_2_4_to_8() because the former function also
      expanded palette images.
```
--- a/src/ref_gl/gl_image.c
+++ b/src/ref_gl/gl_image.c
@@ -1186,7 +1186,7 @@ LoadPNG(char *filename, byte ** pic, int *width, int *height)
 	if (my_png->ColorType == PNG_COLOR_TYPE_PALETTE)
 		png_set_palette_to_rgb(png);
 	if (my_png->ColorType == PNG_COLOR_TYPE_GRAY && my_png->BitDepth < 8)
-		png_set_gray_1_2_4_to_8(png);
+		png_set_expand_gray_1_2_4_to_8(png);
 
 	/* Add alpha channel if present */
 	if (png_get_valid(png, pnginfo, PNG_INFO_tRNS))