diff --git a/ANNOUNCE b/ANNOUNCE
index 88eb016ab..191b0e1ec 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.5.0rc05 - December 31, 2010
+Libpng 1.5.0rc06 - January 4, 2011
 
 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.
@@ -9,20 +9,20 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   1.5.0rc05.tar.xz (LZMA-compressed, recommended)
-   1.5.0rc05.tar.gz
-   1.5.0rc05.tar.bz2
+   1.5.0rc06.tar.xz (LZMA-compressed, recommended)
+   1.5.0rc06.tar.gz
+   1.5.0rc06.tar.bz2
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lp150r05.7z  (LZMA-compressed, recommended)
-   lp150r05.zip
+   lp150r06.7z  (LZMA-compressed, recommended)
+   lp150r06.zip
 
 Other information:
 
-   1.5.0rc05-README.txt
-   1.5.0rc05-LICENSE.txt
+   1.5.0rc06-README.txt
+   1.5.0rc06-LICENSE.txt
 
 Changes since the last public release (1.4.1):
 
@@ -226,7 +226,7 @@ version 1.5.0beta24 [May 7, 2010]
     offset of the png_ptr->rowbuf pointer into png_ptr->big_row_buf.
   Added more blank lines for readability.
 
-version 1.5.0beta25 [December 31, 2010]
+version 1.5.0beta25 [January 4, 2011]
   In pngpread.c: png_push_have_row() add check for new_row > height
   Removed the now-redundant check for out-of-bounds new_row from example.c
 
@@ -478,7 +478,7 @@ Version 1.5.0beta58 [December 19, 2010]
   Fixed the clean rule in Makefile.am to remove pngtest-log.txt
   Made minor changes to work around warnings in gcc 3.4
 
-Version 1.5.0rc01 [December 31, 2010]
+Version 1.5.0rc01 [January 4, 2011]
   No changes.
 
 Version 1.5.0rc02 [December 27, 2010]
@@ -495,6 +495,9 @@ Version 1.5.0rc04 [December 29, 2010]
 version 1.5.0rc05 [December 31, 2010]
   Fixed typo in a comment in CMakeLists.txt (libpng14 => libpng15) (Cosmin)
 
+version 1.5.0rc06 [January 4, 2011]
+  Changed the new configure option "zprefix=string" to "zlib-prefix=string"
+
 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/CHANGES b/CHANGES
index 7a1803cc7..9cc0148fc 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3133,6 +3133,9 @@ Version 1.5.0rc04 [December 29, 2010]
 version 1.5.0rc05 [December 31, 2010]
   Fixed typo in a comment in CMakeLists.txt (libpng14 => libpng15) (Cosmin)
 
+version 1.5.0rc06 [January 4, 2011]
+  Changed the new configure option "zprefix=string" to "zlib-prefix=string"
+
 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/configure b/configure
index 62195a2f6..52a4314f5 100755
--- a/configure
+++ b/configure
@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.68 for libpng-1.5.0rc05
+# Generated by GNU Autoconf 2.68 for libpng 1.5.0rc06
 #
 # Report bugs to <png-mng-implement@lists.sourceforge.net>.
 #
@@ -570,8 +570,8 @@ MAKEFLAGS=
 # Identity of this package.
 PACKAGE_NAME='libpng'
 PACKAGE_TARNAME='libpng'
-PACKAGE_VERSION='1.5.0rc05'
-PACKAGE_STRING='1.5.0rc05'
+PACKAGE_VERSION='1.5.0rc06'
+PACKAGE_STRING='libpng 1.5.0rc06'
 PACKAGE_BUGREPORT='png-mng-implement@lists.sourceforge.net'
 PACKAGE_URL=''
 
@@ -750,7 +750,7 @@ with_pic
 enable_fast_install
 with_sysroot
 enable_libtool_lock
-with_zprefix
+with_zlib_prefix
 with_pkgconfigdir
 with_binconfigs
 '
@@ -1306,7 +1306,7 @@ 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 1.5.0rc05 to adapt to many kinds of systems.
+\`configure' configures libpng 1.5.0rc06 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1376,7 +1376,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of libpng 1.5.0rc05:";;
+     short | recursive ) echo "Configuration of libpng 1.5.0rc06:";;
    esac
   cat <<\_ACEOF
 
@@ -1402,7 +1402,7 @@ Optional Packages:
                           both]
   --with-sysroot=DIR Search for dependent libraries within DIR
                         (or the compiler's sysroot if not specified).
-  --with-zprefix          prefix that may have been used in installed zlib
+  --with-zlib-prefix      prefix that may have been used in installed zlib
   --with-pkgconfigdir     Use the specified pkgconfig dir (default is
                           libdir/pkgconfig)
   --with-binconfigs       Generate shell libpng-config scripts as well as
@@ -1484,7 +1484,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-libpng configure 1.5.0rc05
+libpng configure 1.5.0rc06
 generated by GNU Autoconf 2.68
 
 Copyright (C) 2010 Free Software Foundation, Inc.
@@ -1907,7 +1907,7 @@ 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 1.5.0rc05, which was
+It was created by libpng $as_me 1.5.0rc06, which was
 generated by GNU Autoconf 2.68.  Invocation command line was
 
   $ $0 $@
@@ -2722,7 +2722,7 @@ fi
 
 # Define the identity of the package.
  PACKAGE='libpng'
- VERSION='1.5.0rc05'
+ VERSION='1.5.0rc06'
 
 
 cat >>confdefs.h <<_ACEOF
@@ -2786,7 +2786,7 @@ fi
 
 
 
-PNGLIB_VERSION=1.5.0rc05
+PNGLIB_VERSION=1.5.0rc06
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=5
 PNGLIB_RELEASE=0
@@ -12251,11 +12251,11 @@ fi
 done
 
 
-# Check whether --with-zprefix was given.
-if test "${with_zprefix+set}" = set; then :
-  withval=$with_zprefix; zprefix=${withval}
+# Check whether --with-zlib-prefix was given.
+if test "${with_zlib_prefix+set}" = set; then :
+  withval=$with_zlib_prefix; ZPREFIX=${withval}
 else
-  zprefix='z_'
+  ZPREFIX='z_'
 fi
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for zlibVersion in -lz" >&5
@@ -12302,9 +12302,9 @@ _ACEOF
   LIBS="-lz $LIBS"
 
 else
-  as_ac_Lib=`$as_echo "ac_cv_lib_z_${zprefix}zlibVersion" | $as_tr_sh`
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for ${zprefix}zlibVersion in -lz" >&5
-$as_echo_n "checking for ${zprefix}zlibVersion in -lz... " >&6; }
+  as_ac_Lib=`$as_echo "ac_cv_lib_z_${ZPREFIX}zlibVersion" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for ${ZPREFIX}zlibVersion in -lz" >&5
+$as_echo_n "checking for ${ZPREFIX}zlibVersion in -lz... " >&6; }
 if eval \${$as_ac_Lib+:} false; then :
   $as_echo_n "(cached) " >&6
 else
@@ -12319,11 +12319,11 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char ${zprefix}zlibVersion ();
+char ${ZPREFIX}zlibVersion ();
 int
 main ()
 {
-return ${zprefix}zlibVersion ();
+return ${ZPREFIX}zlibVersion ();
   ;
   return 0;
 }
@@ -12993,7 +12993,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=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 1.5.0rc05, which was
+This file was extended by libpng $as_me 1.5.0rc06, which was
 generated by GNU Autoconf 2.68.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -13059,7 +13059,7 @@ _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-libpng config.status 1.5.0rc05
+libpng config.status 1.5.0rc06
 configured by $0, generated by GNU Autoconf 2.68,
   with options \\"\$ac_cs_config\\"
 
diff --git a/configure.ac b/configure.ac
index 544f27256..580c0abca 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,12 +18,12 @@ AC_PREREQ(2.59)
 
 dnl Version number stuff here:
 
-AC_INIT([libpng], [1.5.0rc05], [png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng], [1.5.0rc06], [png-mng-implement@lists.sourceforge.net])
 AM_INIT_AUTOMAKE
 dnl stop configure from automagically running automake
 AM_MAINTAINER_MODE
 
-PNGLIB_VERSION=1.5.0rc05
+PNGLIB_VERSION=1.5.0rc06
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=5
 PNGLIB_RELEASE=0
@@ -57,13 +57,13 @@ AC_STRUCT_TM
 AC_FUNC_STRTOD
 AC_CHECK_FUNCS([memset], , AC_ERROR([memset not found in libc]))
 AC_CHECK_FUNCS([pow], , AC_CHECK_LIB(m, pow, , AC_ERROR([cannot find pow])) )
-AC_ARG_WITH(zprefix,
-   AC_HELP_STRING([--with-zprefix],
+AC_ARG_WITH(zlib-prefix,
+   AC_HELP_STRING([--with-zlib-prefix],
                   [prefix that may have been used in installed zlib]),
-                  [zprefix=${withval}],
-                  [zprefix='z_'])
+                  [ZPREFIX=${withval}],
+                  [ZPREFIX='z_'])
 AC_CHECK_LIB(z, zlibVersion, ,
-    AC_CHECK_LIB(z, ${zprefix}zlibVersion, ,
+    AC_CHECK_LIB(z, ${ZPREFIX}zlibVersion, ,
                  AC_ERROR([zlib not installed])))