diff --git a/ANNOUNCE b/ANNOUNCE
index 3ff2cbc9..2b471447 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.2.17rc3 - May 9, 2007
+Libpng 1.2.17rc4 - May 12, 2007
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -9,36 +9,36 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   libpng-1.2.17rc3.tar.gz
-   libpng-1.2.17rc3.tar.bz2
+   libpng-1.2.17rc4.tar.gz
+   libpng-1.2.17rc4.tar.bz2
 
 Source files with LF line endings (for Unix/Linux) without the
 "configure" script
 
-   libpng-1.2.17rc3-no-config.tar.gz
-   libpng-1.2.17rc3-no-config.tar.bz2
+   libpng-1.2.17rc4-no-config.tar.gz
+   libpng-1.2.17rc4-no-config.tar.bz2
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lp1217r03.zip
-   lp1217r03.tar.bz2
+   lp1217r04.zip
+   lp1217r04.tar.bz2
 
 Project files
 
-   libpng-1.2.17rc3-project-netware.zip
-   libpng-1.2.17rc3-project-wince.zip
+   libpng-1.2.17rc4-project-netware.zip
+   libpng-1.2.17rc4-project-wince.zip
 
 Other information:
 
-   libpng-1.2.17rc3-README.txt
-   libpng-1.2.17rc3-KNOWNBUGS.txt
-   libpng-1.2.17rc3-LICENSE.txt
-   libpng-1.2.17rc3-Y2K-compliance.txt
+   libpng-1.2.17rc4-README.txt
+   libpng-1.2.17rc4-KNOWNBUGS.txt
+   libpng-1.2.17rc4-LICENSE.txt
+   libpng-1.2.17rc4-Y2K-compliance.txt
 
 Changes since the last public release (1.2.16):
 
-version 1.2.17beta1 [May 9, 2007]
+version 1.2.17beta1 [May 12, 2007]
   Revised scripts/CMakeLists.txt to install both shared and static libraries.
   Deleted a redundant line from pngset.c.
 
@@ -61,9 +61,11 @@ version 1.2.17rc2 [May 8, 2007]
     can be free'ed in case of error.  Revised unknown chunk handling in
     pngrutil.c and pngpread.c to use this structure.
 
-version 1.2.17rc3 [May 9, 2007]
+version 1.2.17rc3 [May 8, 2007]
   Revised symbol-handling in configure script.
 
+version 1.2.17rc4 [May 12, 2007]
+  Revised unknown chunk handling to avoid storing unknown critical chunks.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 
diff --git a/CHANGES b/CHANGES
index a8752856..d5393966 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1714,9 +1714,12 @@ version 1.2.17rc2 [May 8, 2007]
     can be free'ed in case of error.  Revised unknown chunk handling in
     pngrutil.c and pngpread.c to use this structure.
  
-version 1.2.17rc3 [May 9, 2007]
+version 1.2.17rc3 [May 8, 2007]
   Revised symbol-handling in configure script.
 
+version 1.2.17rc4 [May 12, 2007]
+  Revised unknown chunk handling to avoid storing unknown critical chunks.
+
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
diff --git a/INSTALL b/INSTALL
index 928d6e67..0e6c5bf5 100644
--- a/INSTALL
+++ b/INSTALL
@@ -1,5 +1,5 @@
 
-Installing libpng version 1.2.17rc3 - May 9, 2007
+Installing libpng version 1.2.17rc4 - May 12, 2007
 
 On Unix/Linux and similar systems, you can simply type
 
@@ -44,7 +44,7 @@ to have access to the zlib.h and zconf.h include files that
 correspond to the version of zlib that's installed.
 
 You can rename the directories that you downloaded (they
-might be called "libpng-1.2.17rc3" or "lpng109" and "zlib-1.2.1"
+might be called "libpng-1.2.17rc4" or "lpng109" and "zlib-1.2.1"
 or "zlib121") so that you have directories called "zlib" and "libpng".
 
 Your directory structure should look like this:
@@ -101,14 +101,14 @@ include
  CMakeLists.txt    =>  "cmake" script
  makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
  makefile.elf      =>  Linux/ELF makefile symbol versioning,
-                       gcc, creates libpng12.so.0.1.2.17rc3)
+                       gcc, creates libpng12.so.0.1.2.17rc4)
  makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng12.so.0.1.2.17rc3)
+                       (gcc, creates libpng12.so.0.1.2.17rc4)
  makefile.gcmmx    =>  Linux/ELF makefile
-                       (gcc, creates libpng12.so.0.1.2.17rc3,
+                       (gcc, creates libpng12.so.0.1.2.17rc4,
                        uses assembler code tuned for Intel MMX platform)
  makefile.nommx    =>  Linux/ELF makefile
-                       (gcc, creates libpng12.so.0.1.2.17rc3
+                       (gcc, creates libpng12.so.0.1.2.17rc4
                        does not use Intel MMX assembler code)
  makefile.gcc      =>  Generic makefile (gcc, creates static libpng.a)
  makefile.knr      =>  Archaic UNIX Makefile that converts files with
@@ -131,12 +131,12 @@ include
  makefile.openbsd  =>  OpenBSD makefile
  makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
  makefile.sggcc    =>  Silicon Graphics (gcc,
-                       creates libpng12.so.0.1.2.17rc3)
+                       creates libpng12.so.0.1.2.17rc4)
  makefile.sunos    =>  Sun makefile
  makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng12.so.0.1.2.17rc3)
+                       creates libpng12.so.0.1.2.17rc4)
  makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng12.so.0.1.2.17rc3)
+                       creates libpng12.so.0.1.2.17rc4)
  makefile.32sunu   =>  Sun Ultra 32-bit makefile
  makefile.64sunu   =>  Sun Ultra 64-bit makefile
  makefile.sco      =>  For SCO OSr5  ELF and Unixware 7 with Native cc
diff --git a/KNOWNBUG b/KNOWNBUG
index 34bbc6aa..9837bff7 100644
--- a/KNOWNBUG
+++ b/KNOWNBUG
@@ -1,5 +1,5 @@
 
-Known bugs in libpng version 1.2.17rc3
+Known bugs in libpng version 1.2.17rc4
 
 1. April 22, 2001: pnggccrd.c has been reported to crash on NetBSD when
    reading interlaced PNG files, when assembler code is enabled but running
diff --git a/LICENSE b/LICENSE
index 2a7ab2ba..868ef620 100644
--- a/LICENSE
+++ b/LICENSE
@@ -8,7 +8,7 @@ COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
 If you modify libpng you may insert additional notices immediately following
 this sentence.
 
-libpng versions 1.2.6, August 15, 2004, through 1.2.17rc3, May 9, 2007, are
+libpng versions 1.2.6, August 15, 2004, through 1.2.17rc4, May 12, 2007, are
 Copyright (c) 2004, 2006-2007 Glenn Randers-Pehrson, and are
 distributed according to the same disclaimer and license as libpng-1.2.5
 with the following individual added to the list of Contributing Authors
@@ -106,4 +106,4 @@ certification mark of the Open Source Initiative.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-May 9, 2007
+May 12, 2007
diff --git a/README b/README
index dbdcf06a..073a4790 100644
--- a/README
+++ b/README
@@ -1,4 +1,4 @@
-README for libpng version 1.2.17rc3 - May 9, 2007 (shared library 12.0)
+README for libpng version 1.2.17rc4 - May 12, 2007 (shared library 12.0)
 See the note about version numbers near the top of png.h
 
 See INSTALL for instructions on how to install libpng.
@@ -190,11 +190,11 @@ Files in this distribution:
        descrip.mms      =>  VMS makefile for MMS or MMK
        makefile.std     =>  Generic UNIX makefile (cc, creates static libpng.a)
        makefile.elf     =>  Linux/ELF makefile symbol versioning,
-                            gcc, creates libpng12.so.0.1.2.17rc3)
+                            gcc, creates libpng12.so.0.1.2.17rc4)
        makefile.linux   =>  Linux/ELF makefile
-                            (gcc, creates libpng12.so.0.1.2.17rc3)
+                            (gcc, creates libpng12.so.0.1.2.17rc4)
        makefile.gcmmx   =>  Linux/ELF makefile
-                            (gcc, creates libpng12.so.0.1.2.17rc3,
+                            (gcc, creates libpng12.so.0.1.2.17rc4,
                             uses assembler code tuned for Intel MMX platform)
        makefile.gcc     =>  Generic makefile (gcc, creates static libpng.a)
        makefile.knr     =>  Archaic UNIX Makefile that converts files with
@@ -216,12 +216,12 @@ Files in this distribution:
        makefile.openbsd =>  OpenBSD makefile
        makefile.sgi     =>  Silicon Graphics IRIX (cc, creates static lib)
        makefile.sggcc   =>  Silicon Graphics
-                            (gcc, creates libpng12.so.0.1.2.17rc3)
+                            (gcc, creates libpng12.so.0.1.2.17rc4)
        makefile.sunos   =>  Sun makefile
        makefile.solaris =>  Solaris 2.X makefile
-                            (gcc, creates libpng12.so.0.1.2.17rc3)
+                            (gcc, creates libpng12.so.0.1.2.17rc4)
        makefile.so9     =>  Solaris 9 makefile
-                            (gcc, creates libpng12.so.0.1.2.17rc3)
+                            (gcc, creates libpng12.so.0.1.2.17rc4)
        makefile.32sunu  =>  Sun Ultra 32-bit makefile
        makefile.64sunu  =>  Sun Ultra 64-bit makefile
        makefile.sco     =>  For SCO OSr5  ELF and Unixware 7 with Native cc
diff --git a/Y2KINFO b/Y2KINFO
index f9d05c80..98be54c0 100644
--- a/Y2KINFO
+++ b/Y2KINFO
@@ -1,13 +1,13 @@
    Y2K compliance in libpng:
    =========================
 
-      May 9, 2007
+      May 12, 2007
 
       Since the PNG Development group is an ad-hoc body, we can't make
       an official declaration.
 
       This is your unofficial assurance that libpng from version 0.71 and
-      upward through 1.2.17rc3 are Y2K compliant.  It is my belief that earlier
+      upward through 1.2.17rc4 are Y2K compliant.  It is my belief that earlier
       versions were also Y2K compliant.
 
       Libpng only has three year fields.  One is a 2-byte unsigned integer
diff --git a/configure b/configure
index 4538f798..4763f8f0 100755
--- a/configure
+++ b/configure
@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.61 for libpng 1.2.17rc3.
+# Generated by GNU Autoconf 2.61 for libpng 1.2.17rc4.
 #
 # Report bugs to <png-mng-implement@lists.sourceforge.net>.
 #
@@ -728,8 +728,8 @@ SHELL=${CONFIG_SHELL-/bin/sh}
 # Identity of this package.
 PACKAGE_NAME='libpng'
 PACKAGE_TARNAME='libpng'
-PACKAGE_VERSION='1.2.17rc3'
-PACKAGE_STRING='libpng 1.2.17rc3'
+PACKAGE_VERSION='1.2.17rc4'
+PACKAGE_STRING='libpng 1.2.17rc4'
 PACKAGE_BUGREPORT='png-mng-implement@lists.sourceforge.net'
 
 ac_unique_file="pngget.c"
@@ -1406,7 +1406,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures libpng 1.2.17rc3 to adapt to many kinds of systems.
+\`configure' configures libpng 1.2.17rc4 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1476,7 +1476,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of libpng 1.2.17rc3:";;
+     short | recursive ) echo "Configuration of libpng 1.2.17rc4:";;
    esac
   cat <<\_ACEOF
 
@@ -1586,7 +1586,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-libpng configure 1.2.17rc3
+libpng configure 1.2.17rc4
 generated by GNU Autoconf 2.61
 
 Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
@@ -1600,7 +1600,7 @@ cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by libpng $as_me 1.2.17rc3, which was
+It was created by libpng $as_me 1.2.17rc4, which was
 generated by GNU Autoconf 2.61.  Invocation command line was
 
   $ $0 $@
@@ -2270,7 +2270,7 @@ fi
 
 # Define the identity of the package.
  PACKAGE='libpng'
- VERSION='1.2.17rc3'
+ VERSION='1.2.17rc4'
 
 
 cat >>confdefs.h <<_ACEOF
@@ -2441,7 +2441,7 @@ fi
 
 
 
-PNGLIB_VERSION=1.2.17rc3
+PNGLIB_VERSION=1.2.17rc4
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=2
 PNGLIB_RELEASE=17
@@ -21133,7 +21133,7 @@ exec 6>&1
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by libpng $as_me 1.2.17rc3, which was
+This file was extended by libpng $as_me 1.2.17rc4, which was
 generated by GNU Autoconf 2.61.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -21186,7 +21186,7 @@ Report bugs to <bug-autoconf@gnu.org>."
 _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF
 ac_cs_version="\\
-libpng config.status 1.2.17rc3
+libpng config.status 1.2.17rc4
 configured by $0, generated by GNU Autoconf 2.61,
   with options \\"`echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`\\"
 
diff --git a/configure.ac b/configure.ac
index 37b103b4..2588b6b8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,12 +18,12 @@ AC_PREREQ(2.59)
 
 dnl Version number stuff here:
 
-AC_INIT([libpng], [1.2.17rc3], [png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng], [1.2.17rc4], [png-mng-implement@lists.sourceforge.net])
 AM_INIT_AUTOMAKE
 dnl stop configure from automagically running automake
 AM_MAINTAINER_MODE
 
-PNGLIB_VERSION=1.2.17rc3
+PNGLIB_VERSION=1.2.17rc4
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=2
 PNGLIB_RELEASE=17
diff --git a/libpng-1.2.17rc3.txt b/libpng-1.2.17rc4.txt
similarity index 99%
rename from libpng-1.2.17rc3.txt
rename to libpng-1.2.17rc4.txt
index 5f717507..698173a2 100644
--- a/libpng-1.2.17rc3.txt
+++ b/libpng-1.2.17rc4.txt
@@ -1,9 +1,9 @@
 libpng.txt - A description on how to use and modify libpng
 
- libpng version 1.2.17rc3 - May 9, 2007
+ libpng version 1.2.17rc4 - May 12, 2007
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
- Copyright (c) 1998-2005 Glenn Randers-Pehrson
+ Copyright (c) 1998-2007 Glenn Randers-Pehrson
  For conditions of distribution and use, see copyright
  notice in png.h.
 
@@ -2921,13 +2921,13 @@ application:
 
 IX. Y2K Compliance in libpng
 
-May 9, 2007
+May 12, 2007
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.2.17rc3 are Y2K compliant.  It is my belief that earlier
+upward through 1.2.17rc4 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
 Libpng only has three year fields.  One is a 2-byte unsigned integer that
diff --git a/libpng.3 b/libpng.3
index c34405d7..d0d15bf2 100644
--- a/libpng.3
+++ b/libpng.3
@@ -1,6 +1,6 @@
-.TH LIBPNG 3 "May 9, 2007"
+.TH LIBPNG 3 "May 12, 2007"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.2.17rc3
+libpng \- Portable Network Graphics (PNG) Reference Library 1.2.17rc4
 .SH SYNOPSIS
 \fB
 #include <png.h>\fP
@@ -410,10 +410,10 @@ Following is a copy of the libpng.txt file that accompanies libpng.
 .SH LIBPNG.TXT
 libpng.txt - A description on how to use and modify libpng
 
- libpng version 1.2.17rc3 - May 9, 2007
+ libpng version 1.2.17rc4 - May 12, 2007
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
- Copyright (c) 1998-2005 Glenn Randers-Pehrson
+ Copyright (c) 1998-2007 Glenn Randers-Pehrson
  For conditions of distribution and use, see copyright
  notice in png.h.
 
@@ -3331,13 +3331,13 @@ application:
 
 .SH IX. Y2K Compliance in libpng
 
-May 9, 2007
+May 12, 2007
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.2.17rc3 are Y2K compliant.  It is my belief that earlier
+upward through 1.2.17rc4 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
 Libpng only has three year fields.  One is a 2-byte unsigned integer that
@@ -3577,7 +3577,7 @@ possible without all of you.
 
 Thanks to Frank J. T. Wojcik for helping with the documentation.
 
-Libpng version 1.2.17rc3 - May 9, 2007:
+Libpng version 1.2.17rc4 - May 12, 2007:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
 
@@ -3598,7 +3598,7 @@ included in the libpng distribution, the latter shall prevail.)
 If you modify libpng you may insert additional notices immediately following
 this sentence.
 
-libpng versions 1.2.6, August 15, 2004, through 1.2.17rc3, May 9, 2007, are
+libpng versions 1.2.6, August 15, 2004, through 1.2.17rc4, May 12, 2007, are
 Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are
 distributed according to the same disclaimer and license as libpng-1.2.5
 with the following individual added to the list of Contributing Authors
@@ -3697,7 +3697,7 @@ certification mark of the Open Source Initiative.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-May 9, 2007
+May 12, 2007
 
 .\" end of man page
 
diff --git a/libpngpf.3 b/libpngpf.3
index a06e0c94..a1f25b3d 100644
--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "May 9, 2007"
+.TH LIBPNGPF 3 "May 12, 2007"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.2.17rc3
+libpng \- Portable Network Graphics (PNG) Reference Library 1.2.17rc4
 (private functions)
 .SH SYNOPSIS
 \fB#include <png.h>\fP
diff --git a/png.5 b/png.5
index 0b1460e6..e320197a 100644
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "May 9, 2007"
+.TH PNG 5 "May 12, 2007"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
diff --git a/png.c b/png.c
index 820e5f66..76d4d60d 100644
--- a/png.c
+++ b/png.c
@@ -1,7 +1,7 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.2.17 May 9, 2007
+ * Last changed in libpng 1.2.17 May 12, 2007
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2007 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -13,7 +13,7 @@
 #include "png.h"
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef version_1_2_17rc3 Your_png_h_is_not_version_1_2_17rc3;
+typedef version_1_2_17rc4 Your_png_h_is_not_version_1_2_17rc4;
 
 /* Version information for C files.  This had better match the version
  * string defined in png.h.  */
@@ -706,7 +706,7 @@ png_charp PNGAPI
 png_get_copyright(png_structp png_ptr)
 {
    if (&png_ptr != NULL)  /* silence compiler warning about unused png_ptr */
-   return ((png_charp) "\n libpng version 1.2.17rc3 - May 9, 2007\n\
+   return ((png_charp) "\n libpng version 1.2.17rc4 - May 12, 2007\n\
    Copyright (c) 1998-2007 Glenn Randers-Pehrson\n\
    Copyright (c) 1996-1997 Andreas Dilger\n\
    Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.\n");
diff --git a/png.h b/png.h
index 065fa975..b2f80067 100644
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.2.17rc3 - May 9, 2007
+ * libpng version 1.2.17rc4 - May 12, 2007
  * Copyright (c) 1998-2007 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -9,7 +9,7 @@
  * Authors and maintainers:
  *  libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  *  libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
- *  libpng versions 0.97, January 1998, through 1.2.17rc3 - May 9, 2007: Glenn
+ *  libpng versions 0.97, January 1998, through 1.2.17rc4 - May 12, 2007: Glenn
  *  See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
@@ -175,7 +175,7 @@
  * If you modify libpng you may insert additional notices immediately following
  * this sentence.
  *
- * libpng versions 1.2.6, August 15, 2004, through 1.2.17rc3, May 9, 2007, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.2.17rc4, May 12, 2007, are
  * Copyright (c) 2004, 2006-2007 Glenn Randers-Pehrson, and are
  * distributed according to the same disclaimer and license as libpng-1.2.5
  * with the following individual added to the list of Contributing Authors:
@@ -287,13 +287,13 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    May 9, 2007
+ *    May 12, 2007
  *
  *    Since the PNG Development group is an ad-hoc body, we can't make
  *    an official declaration.
  *
  *    This is your unofficial assurance that libpng from version 0.71 and
- *    upward through 1.2.17rc3 are Y2K compliant.  It is my belief that earlier
+ *    upward through 1.2.17rc4 are Y2K compliant.  It is my belief that earlier
  *    versions were also Y2K compliant.
  *
  *    Libpng only has three year fields.  One is a 2-byte unsigned integer
@@ -349,9 +349,9 @@
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.2.17rc3"
+#define PNG_LIBPNG_VER_STRING "1.2.17rc4"
 #define PNG_HEADER_VERSION_STRING \
-   " libpng version 1.2.17rc3 - May 9, 2007 (header)\n"
+   " libpng version 1.2.17rc4 - May 12, 2007 (header)\n"
 
 #define PNG_LIBPNG_VER_SONUM   0
 #define PNG_LIBPNG_VER_DLLNUM  13
@@ -363,7 +363,7 @@
 /* This should match the numeric part of the final component of
  * PNG_LIBPNG_VER_STRING, omitting any leading zero: */
 
-#define PNG_LIBPNG_VER_BUILD  3
+#define PNG_LIBPNG_VER_BUILD  4
 
 /* Release Status */
 #define PNG_LIBPNG_BUILD_ALPHA    1
@@ -1402,7 +1402,7 @@ struct png_struct_def
 /* This triggers a compiler error in png.c, if png.c and png.h
  * do not agree upon the version number.
  */
-typedef png_structp version_1_2_17rc3;
+typedef png_structp version_1_2_17rc4;
 
 typedef png_struct FAR * FAR * png_structpp;
 
diff --git a/pngconf.h b/pngconf.h
index 9482c509..8ab619f4 100644
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.2.17rc3 - May 9, 2007
+ * libpng version 1.2.17rc4 - May 12, 2007
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2007 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
diff --git a/pngpread.c b/pngpread.c
index 05d772c0..0fbf0d41 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -1,7 +1,7 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Last changed in libpng 1.2.17 May 9, 2007
+ * Last changed in libpng 1.2.17 May 12, 2007
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2007 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -1516,10 +1516,13 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
                 if(png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
                      PNG_HANDLE_CHUNK_ALWAYS)
                    png_chunk_error(png_ptr, "unknown critical chunk");
+                png_set_unknown_chunks(png_ptr, info_ptr,
+                   &png_ptr->unknown_chunk, 1);
           }
        }
-#endif
+#else
        png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
+#endif
        png_free(png_ptr, png_ptr->unknown_chunk.data);
        png_ptr->unknown_chunk.data = NULL;
    }
diff --git a/pngrutil.c b/pngrutil.c
index 8cd186ec..7f74c512 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.2.17 May 9, 2007
+ * Last changed in libpng 1.2.17 May 12, 2007
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2007 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -2201,10 +2201,13 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
                 if(png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
                      PNG_HANDLE_CHUNK_ALWAYS)
                    png_chunk_error(png_ptr, "unknown critical chunk");
+             png_set_unknown_chunks(png_ptr, info_ptr,
+               &png_ptr->unknown_chunk, 1);
           }
        }
-#endif
+#else
        png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
+#endif
        png_free(png_ptr, png_ptr->unknown_chunk.data);
        png_ptr->unknown_chunk.data = NULL;
    }
diff --git a/pngset.c b/pngset.c
index 47f67e57..f4acbfca 100644
--- a/pngset.c
+++ b/pngset.c
@@ -1,7 +1,7 @@
 
 /* pngset.c - storage of image information into info struct
  *
- * Last changed in libpng 1.2.17 May 9, 2007
+ * Last changed in libpng 1.2.17 May 12, 2007
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2007 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
diff --git a/pngtest.c b/pngtest.c
index c311d11e..c0f83598 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -1551,4 +1551,4 @@ main(int argc, char *argv[])
 }
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef version_1_2_17rc3 your_png_h_is_not_version_1_2_17rc3;
+typedef version_1_2_17rc4 your_png_h_is_not_version_1_2_17rc4;
diff --git a/scripts/CMakeLists.txt b/scripts/CMakeLists.txt
index c05784c7..9850c18b 100644
--- a/scripts/CMakeLists.txt
+++ b/scripts/CMakeLists.txt
@@ -179,7 +179,7 @@ configure_file(${PNG_SOURCE_DIR}/scripts/libpng-config.in
 
 # SET UP LINKS
 set_target_properties(${PNG_LIB_NAME} PROPERTIES
-#    VERSION 0.${PNGLIB_RELEASE}.1.2.17rc3
+#    VERSION 0.${PNGLIB_RELEASE}.1.2.17rc4
      VERSION 0.${PNGLIB_RELEASE}.0
      SOVERSION 0
      CLEAN_DIRECT_OUTPUT 1)
diff --git a/scripts/libpng-config-head.in b/scripts/libpng-config-head.in
index 1e71136e..5dcc458e 100755
--- a/scripts/libpng-config-head.in
+++ b/scripts/libpng-config-head.in
@@ -8,7 +8,7 @@
 
 # Modeled after libxml-config.
 
-version=1.2.17rc3
+version=1.2.17rc4
 prefix=""
 libdir=""
 libs=""
diff --git a/scripts/libpng.pc-configure.in b/scripts/libpng.pc-configure.in
index 3e57e98d..ed20b136 100644
--- a/scripts/libpng.pc-configure.in
+++ b/scripts/libpng.pc-configure.in
@@ -5,6 +5,6 @@ includedir=@includedir@/libpng12
 
 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.2.17rc3
+Version: 1.2.17rc4
 Libs: -L${libdir} -lpng12
 Cflags: -I${includedir} @LIBPNG_NO_MMX@
diff --git a/scripts/libpng.pc.in b/scripts/libpng.pc.in
index d0d9c35e..a5a68c22 100644
--- a/scripts/libpng.pc.in
+++ b/scripts/libpng.pc.in
@@ -5,6 +5,6 @@ includedir=@includedir@/libpng12
 
 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.2.17rc3
+Version: 1.2.17rc4
 Libs: -L${libdir} -lpng12
 Cflags: -I${includedir}
diff --git a/scripts/makefile.32sunu b/scripts/makefile.32sunu
index 562e378e..13060112 100644
--- a/scripts/makefile.32sunu
+++ b/scripts/makefile.32sunu
@@ -8,7 +8,7 @@
 # Library name:
 LIBNAME=libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.64sunu b/scripts/makefile.64sunu
index 34baaeba..19180f70 100644
--- a/scripts/makefile.64sunu
+++ b/scripts/makefile.64sunu
@@ -8,7 +8,7 @@
 # Library name:
 LIBNAME=libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.aix b/scripts/makefile.aix
index 742222b9..208594c7 100644
--- a/scripts/makefile.aix
+++ b/scripts/makefile.aix
@@ -20,7 +20,7 @@ LN_SF = ln -f -s
 
 LIBNAME=libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 prefix=/usr/local
diff --git a/scripts/makefile.beos b/scripts/makefile.beos
index 5cfbe9bd..7ddbfc3b 100644
--- a/scripts/makefile.beos
+++ b/scripts/makefile.beos
@@ -8,7 +8,7 @@
 # Library name:
 LIBNAME=libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.cygwin b/scripts/makefile.cygwin
index 97915b62..406725e6 100644
--- a/scripts/makefile.cygwin
+++ b/scripts/makefile.cygwin
@@ -80,7 +80,7 @@ CFLAGS= $(strip $(MINGW_CCFLAGS) $(addprefix -I,$(ZLIBINC)) \
 LIBNAME = libpng12
 PNGMAJ = 0
 CYGDLL = 12
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 SHAREDLIB=cygpng$(CYGDLL).dll
diff --git a/scripts/makefile.darwin b/scripts/makefile.darwin
index 9296f14e..2bc8d083 100644
--- a/scripts/makefile.darwin
+++ b/scripts/makefile.darwin
@@ -19,7 +19,7 @@ ZLIBINC=../zlib
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.dec b/scripts/makefile.dec
index 4a55b22a..ab537dcc 100644
--- a/scripts/makefile.dec
+++ b/scripts/makefile.dec
@@ -5,7 +5,7 @@
 
 # Library name:
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 LIBNAME = libpng12
 
diff --git a/scripts/makefile.elf b/scripts/makefile.elf
index 57e404f0..f9008e0b 100644
--- a/scripts/makefile.elf
+++ b/scripts/makefile.elf
@@ -12,7 +12,7 @@
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.gcmmx b/scripts/makefile.gcmmx
index 8ce7b2ea..83daaa01 100644
--- a/scripts/makefile.gcmmx
+++ b/scripts/makefile.gcmmx
@@ -16,7 +16,7 @@
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.hp64 b/scripts/makefile.hp64
index 55da66eb..db2bb1bb 100644
--- a/scripts/makefile.hp64
+++ b/scripts/makefile.hp64
@@ -18,7 +18,7 @@ ZLIBINC=/opt/zlib/include
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.hpgcc b/scripts/makefile.hpgcc
index 01845a38..214b037b 100644
--- a/scripts/makefile.hpgcc
+++ b/scripts/makefile.hpgcc
@@ -8,7 +8,7 @@
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.hpux b/scripts/makefile.hpux
index 13aa3be0..f651c56a 100644
--- a/scripts/makefile.hpux
+++ b/scripts/makefile.hpux
@@ -18,7 +18,7 @@ ZLIBINC=/opt/zlib/include
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.linux b/scripts/makefile.linux
index 97ec1dd5..16ca8e27 100644
--- a/scripts/makefile.linux
+++ b/scripts/makefile.linux
@@ -6,7 +6,7 @@
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.mingw b/scripts/makefile.mingw
index 44be8c09..ec9cd509 100644
--- a/scripts/makefile.mingw
+++ b/scripts/makefile.mingw
@@ -76,7 +76,7 @@ CFLAGS= $(strip $(MINGW_CCFLAGS) $(addprefix -I,$(ZLIBINC)) \
 LIBNAME = libpng12
 PNGMAJ = 0
 MINGDLL = 12
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 SHAREDLIB=libpng$(MINGDLL).dll
diff --git a/scripts/makefile.ne12bsd b/scripts/makefile.ne12bsd
index 0fb66822..73ab8ee3 100644
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -14,7 +14,7 @@ INCSDIR=${LOCALBASE}/include/libpng12
 
 LIB=	png12
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.2.17rc3
+SHLIB_MINOR=	1.2.17rc4
 SRCS=	pnggccrd.c png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 		pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 		pngwtran.c pngmem.c pngerror.c pngpread.c
diff --git a/scripts/makefile.netbsd b/scripts/makefile.netbsd
index cd1e0d01..f39e6ba5 100644
--- a/scripts/makefile.netbsd
+++ b/scripts/makefile.netbsd
@@ -14,7 +14,7 @@ INCSDIR=${LOCALBASE}/include/libpng
 
 LIB=	png
 SHLIB_MAJOR=	3
-SHLIB_MINOR=	1.2.17rc3
+SHLIB_MINOR=	1.2.17rc4
 SRCS=	pnggccrd.c png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 		pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 		pngwtran.c pngmem.c pngerror.c pngpread.c
diff --git a/scripts/makefile.nommx b/scripts/makefile.nommx
index 7263940b..4c6613e9 100644
--- a/scripts/makefile.nommx
+++ b/scripts/makefile.nommx
@@ -7,7 +7,7 @@
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.openbsd b/scripts/makefile.openbsd
index 9ea89623..45bb868f 100644
--- a/scripts/makefile.openbsd
+++ b/scripts/makefile.openbsd
@@ -8,7 +8,7 @@ LIBDIR=	${PREFIX}/lib
 MANDIR= ${PREFIX}/man/cat
 
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.2.17rc3
+SHLIB_MINOR=	1.2.17rc4
 
 LIB=	png
 SRCS=	png.c pngerror.c pnggccrd.c pngget.c pngmem.c pngpread.c \
diff --git a/scripts/makefile.sco b/scripts/makefile.sco
index 74725c3b..eec0b995 100644
--- a/scripts/makefile.sco
+++ b/scripts/makefile.sco
@@ -9,7 +9,7 @@
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.sggcc b/scripts/makefile.sggcc
index b3c04a1f..77dcae3d 100644
--- a/scripts/makefile.sggcc
+++ b/scripts/makefile.sggcc
@@ -6,7 +6,7 @@
 # Library name:
 LIBNAME=libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.sgi b/scripts/makefile.sgi
index c9ec5479..cf7b7404 100644
--- a/scripts/makefile.sgi
+++ b/scripts/makefile.sgi
@@ -6,7 +6,7 @@
 # Library name:
 LIBNAME=libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/makefile.so9 b/scripts/makefile.so9
index 788a2c56..5d809cd0 100644
--- a/scripts/makefile.so9
+++ b/scripts/makefile.so9
@@ -8,7 +8,7 @@
 
 # Library name:
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 LIBNAME = libpng12
 
diff --git a/scripts/makefile.solaris b/scripts/makefile.solaris
index 444c6b93..1a7f1ed5 100644
--- a/scripts/makefile.solaris
+++ b/scripts/makefile.solaris
@@ -8,7 +8,7 @@
 # Library name:
 LIBNAME = libpng12
 PNGMAJ = 0
-PNGMIN = 1.2.17rc3
+PNGMIN = 1.2.17rc4
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # Shared library names:
diff --git a/scripts/pngos2.def b/scripts/pngos2.def
index cb5e8377..3fed7482 100644
--- a/scripts/pngos2.def
+++ b/scripts/pngos2.def
@@ -2,7 +2,7 @@
 ; PNG.LIB module definition file for OS/2
 ;----------------------------------------
 
-; Version 1.2.17rc3
+; Version 1.2.17rc4
 
 LIBRARY		PNG
 DESCRIPTION	"PNG image compression library for OS/2"
diff --git a/scripts/pngw32.def b/scripts/pngw32.def
index a0631011..ac5b3652 100644
--- a/scripts/pngw32.def
+++ b/scripts/pngw32.def
@@ -5,7 +5,7 @@
 LIBRARY
 
 EXPORTS
-;Version 1.2.17rc3
+;Version 1.2.17rc4
   png_build_grayscale_palette  @1
   png_check_sig        @2
   png_chunk_error      @3