diff -ur hp2xx-3.4.4/sources/Makefile hp2xx-3.4.4-new/sources/Makefile
--- hp2xx-3.4.4/sources/Makefile	2003-06-21 16:16:34.000000000 +0100
+++ hp2xx-3.4.4-new/sources/Makefile	2013-08-10 01:09:43.938058174 +0100
@@ -195,7 +195,7 @@
 EX_SRC  += png.c to_png.c
 EX_OBJ  += png.o to_png.o
 EX_DEFS += -DPNG
-EX_LIBS += -lpng -lz
+EX_LIBS += -lpng12 -lz
 #
 # Include TIFF support:
 EX_SRC  += to_tif.c
diff -ur hp2xx-3.4.4/sources/png.c hp2xx-3.4.4-new/sources/png.c
--- hp2xx-3.4.4/sources/png.c	2003-06-21 16:31:51.000000000 +0100
+++ hp2xx-3.4.4-new/sources/png.c	2013-08-10 01:10:06.578058462 +0100
@@ -5,7 +5,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include "to_png.h"
-#include <png.h>
+#include <libpng12/png.h>
 
 #define PDNCOL 256