diff --git a/png.c b/png.c
index b5fbc1497..0f9f964ce 100644
--- a/png.c
+++ b/png.c
@@ -14,7 +14,7 @@
 #include "pngpriv.h"
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef version_1_5_0beta24 Your_png_h_is_not_version_1_5_0beta24;
+typedef version_1_5_0beta23 Your_png_h_is_not_version_1_5_0beta23;
 
 /* Version information for C files.  This had better match the version
  * string defined in png.h.
@@ -548,13 +548,13 @@ png_get_copyright(png_structp png_ptr)
 #else
 #  ifdef __STDC__
    return ((png_charp) PNG_STRING_NEWLINE \
-     "libpng version 1.5.0beta24 - April 29, 2010" PNG_STRING_NEWLINE \
+     "libpng version 1.5.0beta23 - April 29, 2010" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2010 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
      PNG_STRING_NEWLINE);
 #  else
-      return ((png_charp) "libpng version 1.5.0beta24 - April 29, 2010\
+      return ((png_charp) "libpng version 1.5.0beta23 - April 29, 2010\
       Copyright (c) 1998-2010 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.");
@@ -629,7 +629,7 @@ png_reset_zstream(png_structp png_ptr)
       return Z_STREAM_ERROR;
    return (inflateReset(&png_ptr->zstream));
 }
-#endif /* PNG_WRITE_SUPPORTED */
+#endif /* PNG_READ_SUPPORTED */
 
 /* This function was added to libpng-1.0.7 */
 png_uint_32 PNGAPI
diff --git a/png.h b/png.h
index 881e629dd..d523d317a 100644
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.5.0beta24 - April 29, 2010
+ * libpng version 1.5.0beta23 - April 29, 2010
  * Copyright (c) 1998-2010 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.)
@@ -11,7 +11,7 @@
  * 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 1.5.0beta24 - April 29, 2010: Glenn
+ *   libpng versions 0.97, January 1998, through 1.5.0beta23 - April 29, 2010: Glenn
  *   See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
@@ -170,7 +170,7 @@
  *
  * This code is released under the libpng license.
  *
- * libpng versions 1.2.6, August 15, 2004, through 1.5.0beta24, April 29, 2010, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.5.0beta23, April 29, 2010, are
  * Copyright (c) 2004, 2006-2010 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:
@@ -288,7 +288,7 @@
  *    an official declaration.
  *
  *    This is your unofficial assurance that libpng from version 0.71 and
- *    upward through 1.5.0beta24 are Y2K compliant.  It is my belief that earlier
+ *    upward through 1.5.0beta23 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
@@ -344,9 +344,9 @@
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.5.0beta24"
+#define PNG_LIBPNG_VER_STRING "1.5.0beta23"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.5.0beta24 - April 29, 2010\n"
+     " libpng version 1.5.0beta23 - April 29, 2010\n"
 
 #define PNG_LIBPNG_VER_SONUM   15
 #define PNG_LIBPNG_VER_DLLNUM  15
@@ -359,7 +359,7 @@
  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
  */
 
-#define PNG_LIBPNG_VER_BUILD  24
+#define PNG_LIBPNG_VER_BUILD  23
 
 /* Release Status */
 #define PNG_LIBPNG_BUILD_ALPHA    1
@@ -834,7 +834,7 @@ typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp),);
 /* 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_5_0beta24;
+typedef png_structp version_1_5_0beta23;
 
 typedef png_struct FAR * FAR * png_structpp;
 
@@ -910,8 +910,10 @@ extern PNG_EXPORT(jmp_buf*, png_set_longjmp_fn, (png_structp png_ptr,
 extern PNG_EXPORT(void, png_longjmp, (png_structp png_ptr, int val),
     PNG_NORETURN,9);
 
+#ifdef PNG_READ_SUPPORTED
 /* Reset the compression stream */
 extern PNG_EXPORT(int,png_reset_zstream,(png_structp png_ptr),,10);
+#endif
 
 /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
 #ifdef PNG_USER_MEM_SUPPORTED