diff -ur pngcheck-2.3.0/Makefile.unx pngcheck-2.3.0_fix//Makefile.unx
--- pngcheck-2.3.0/Makefile.unx	2006-06-18 00:47:35.000000000 +0200
+++ pngcheck-2.3.0_fix//Makefile.unx	2009-08-30 12:26:49.000000000 +0200
@@ -18,18 +18,12 @@
 
 # macros --------------------------------------------------------------------
 
-ZPATH = ../zlib
-ZINC = -I$(ZPATH)
-#ZLIB = -L$(ZPATH) -lz
-ZLIB = $(ZPATH)/libz.a
-
-INCS = $(ZINC)
-LIBS = $(ZLIB)
+LIBS = -lz
 
 CC = gcc
 LD = gcc
 RM = rm
-CFLAGS = -O -Wall $(INCS) -DUSE_ZLIB
+CFLAGS = -O -Wall -DUSE_ZLIB
 # [note that -Wall is a gcc-specific compilation flag ("all warnings on")]
 O = .o
 E =
Nur in pngcheck-2.3.0_fix/: Makefile.unx~.