diff --git a/Changes.txt b/Changes.txt
index 3f7203c15..242ffeb08 100644
--- a/Changes.txt
+++ b/Changes.txt
@@ -12,6 +12,15 @@
                                Release History
 ===========================================================================
 
+3.5.5 to 3.6: (March xx, 2012)
+
+
+
+  * Updated included PNG library to latest stable version.
+
+-Have fun!
+
+
 3.5 to 3.5.5: (February 4, 2012)
 
   * Due to changes in the debugger, old state files will not work with
@@ -71,8 +80,6 @@
 
   * Updated included PNG library to latest stable version.
 
--Have fun!
-
 
 3.4.1 to 3.5: (December 29, 2011)
 
diff --git a/src/libpng/png.c b/src/libpng/png.c
index 83e4955b1..ca1de4866 100644
--- a/src/libpng/png.c
+++ b/src/libpng/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 png_libpng_version_1_5_8 Your_png_h_is_not_version_1_5_8;
+typedef png_libpng_version_1_5_9 Your_png_h_is_not_version_1_5_9;
 
 /* Tells libpng that we have already handled the first "num_bytes" bytes
  * of the PNG file signature.  If the PNG data is embedded into another
@@ -655,13 +655,13 @@ png_get_copyright(png_const_structp png_ptr)
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-     "libpng version 1.5.8 - February 1, 2012" PNG_STRING_NEWLINE \
+     "libpng version 1.5.9 - February 18, 2012" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2011 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 "libpng version 1.5.8 - February 1, 2012\
+      return "libpng version 1.5.9 - February 18, 2012\
       Copyright (c) 1998-2011 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
diff --git a/src/libpng/png.h b/src/libpng/png.h
index bebaf5497..5617c9720 100644
--- a/src/libpng/png.h
+++ b/src/libpng/png.h
@@ -1,7 +1,7 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.5.8 - February 1, 2012
+ * libpng version 1.5.9 - February 18, 2012
  * Copyright (c) 1998-2012 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 1.5.8 - February 1, 2012: Glenn
+ *   libpng versions 0.97, January 1998, through 1.5.9 - February 18, 2012: Glenn
  *   See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
@@ -168,6 +168,10 @@
  *    1.5.7                   15    10507  15.so.15.7[.0]
  *    1.5.8beta01             15    10508  15.so.15.8[.0]
  *    1.5.8rc01               15    10508  15.so.15.8[.0]
+ *    1.5.8                   15    10508  15.so.15.8[.0]
+ *    1.5.9beta01-02          15    10509  15.so.15.9[.0]
+ *    1.5.9rc01               15    10509  15.so.15.9[.0]
+ *    1.5.9                   15    10509  15.so.15.9[.0]
  *
  *   Henceforth the source version will match the shared-library major
  *   and minor numbers; the shared-library major version number will be
@@ -199,7 +203,7 @@
  *
  * This code is released under the libpng license.
  *
- * libpng versions 1.2.6, August 15, 2004, through 1.5.8, February 1, 2012, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.5.9, February 18, 2012, are
  * Copyright (c) 2004, 2006-2012 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:
@@ -311,13 +315,13 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    February 1, 2012
+ *    February 18, 2012
  *
  *    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 1.5.8 are Y2K compliant.  It is my belief that
+ *    upward through 1.5.9 are Y2K compliant.  It is my belief that
  *    earlier versions were also Y2K compliant.
  *
  *    Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -375,9 +379,9 @@
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.5.8"
+#define PNG_LIBPNG_VER_STRING "1.5.9"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.5.8 - February 1, 2012\n"
+     " libpng version 1.5.9 - February 18, 2012\n"
 
 #define PNG_LIBPNG_VER_SONUM   15
 #define PNG_LIBPNG_VER_DLLNUM  15
@@ -385,7 +389,7 @@
 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 #define PNG_LIBPNG_VER_MAJOR   1
 #define PNG_LIBPNG_VER_MINOR   5
-#define PNG_LIBPNG_VER_RELEASE 8
+#define PNG_LIBPNG_VER_RELEASE 9
 
 /* This should match the numeric part of the final component of
  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
@@ -416,7 +420,7 @@
  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
  */
-#define PNG_LIBPNG_VER 10508 /* 1.5.8 */
+#define PNG_LIBPNG_VER 10509 /* 1.5.9 */
 
 /* Library configuration: these options cannot be changed after
  * the library has been built.
@@ -538,7 +542,7 @@ extern "C" {
 /* This triggers a compiler error in png.c, if png.c and png.h
  * do not agree upon the version number.
  */
-typedef char* png_libpng_version_1_5_8;
+typedef char* png_libpng_version_1_5_9;
 
 /* Three color definitions.  The order of the red, green, and blue, (and the
  * exact size) is not important, although the size of the fields need to
diff --git a/src/libpng/pngconf.h b/src/libpng/pngconf.h
index 6c1db14ea..1aa268bee 100644
--- a/src/libpng/pngconf.h
+++ b/src/libpng/pngconf.h
@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.5.8 - February 1, 2012
+ * libpng version 1.5.9 - February 18, 2012
  *
  * Copyright (c) 1998-2012 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
diff --git a/src/libpng/pngerror.c b/src/libpng/pngerror.c
index 00ed0fe69..95002f84f 100644
--- a/src/libpng/pngerror.c
+++ b/src/libpng/pngerror.c
@@ -1,7 +1,7 @@
 
 /* pngerror.c - stub functions for i/o and memory allocation
  *
- * Last changed in libpng 1.5.7 [February 1, 2012]
+ * Last changed in libpng 1.5.8 [February 1, 2011]
  * Copyright (c) 1998-2012 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.)
diff --git a/src/libpng/pngpread.c b/src/libpng/pngpread.c
index 20d3f236e..95a2082e4 100644
--- a/src/libpng/pngpread.c
+++ b/src/libpng/pngpread.c
@@ -1,7 +1,7 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Last changed in libpng 1.5.7 [December 15, 2011]
+ * Last changed in libpng 1.5.9 [February 18, 2012]
  * Copyright (c) 1998-2011 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.)
@@ -730,8 +730,7 @@ png_push_save_buffer(png_structp png_ptr)
 
       new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
       old_buffer = png_ptr->save_buffer;
-      png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
-          (png_size_t)new_max);
+      png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr, new_max);
 
       if (png_ptr->save_buffer == NULL)
       {
@@ -1201,6 +1200,7 @@ png_push_process_row(png_structp png_ptr)
 void /* PRIVATE */
 png_read_push_finish_row(png_structp png_ptr)
 {
+#ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
@@ -1219,6 +1219,7 @@ png_read_push_finish_row(png_structp png_ptr)
     * it, uncomment it here and in png.h
    static PNG_CONST png_byte FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
    */
+#endif
 
    png_ptr->row_number++;
    if (png_ptr->row_number < png_ptr->num_rows)
@@ -1285,8 +1286,7 @@ png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
    }
 #endif
 
-   png_ptr->current_text = (png_charp)png_malloc(png_ptr,
-       (png_size_t)(length + 1));
+   png_ptr->current_text = (png_charp)png_malloc(png_ptr, length + 1);
    png_ptr->current_text[length] = '\0';
    png_ptr->current_text_ptr = png_ptr->current_text;
    png_ptr->current_text_size = (png_size_t)length;
@@ -1384,8 +1384,7 @@ png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
    }
 #endif
 
-   png_ptr->current_text = (png_charp)png_malloc(png_ptr,
-       (png_size_t)(length + 1));
+   png_ptr->current_text = (png_charp)png_malloc(png_ptr, length + 1);
    png_ptr->current_text[length] = '\0';
    png_ptr->current_text_ptr = png_ptr->current_text;
    png_ptr->current_text_size = (png_size_t)length;
@@ -1586,8 +1585,7 @@ png_push_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
    }
 #endif
 
-   png_ptr->current_text = (png_charp)png_malloc(png_ptr,
-       (png_size_t)(length + 1));
+   png_ptr->current_text = (png_charp)png_malloc(png_ptr, length + 1);
    png_ptr->current_text[length] = '\0';
    png_ptr->current_text_ptr = png_ptr->current_text;
    png_ptr->current_text_size = (png_size_t)length;
@@ -1732,8 +1730,7 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
        */
       PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
 
-      /* The following cast should be safe because of the check above. */
-      png_ptr->unknown_chunk.size = (png_size_t)length;
+      png_ptr->unknown_chunk.size = length;
 
       if (length == 0)
          png_ptr->unknown_chunk.data = NULL;
diff --git a/src/libpng/pngrutil.c b/src/libpng/pngrutil.c
index 52a73cfc3..d6c0e0350 100644
--- a/src/libpng/pngrutil.c
+++ b/src/libpng/pngrutil.c
@@ -1,8 +1,8 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.5.7 [December 15, 2011]
- * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * Last changed in libpng 1.5.9 [February 18, 2012]
+ * Copyright (c) 1998-2012 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.)
  *
@@ -432,15 +432,18 @@ png_decompress_chunk(png_structp png_ptr, int comp_type,
       /* Now check the limits on this chunk - if the limit fails the
        * compressed data will be removed, the prefix will remain.
        */
+      if (prefix_size >= (~(png_size_t)0) - 1 ||
+         expanded_size >= (~(png_size_t)0) - 1 - prefix_size
 #ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
-      if (png_ptr->user_chunk_malloc_max &&
+         || (png_ptr->user_chunk_malloc_max &&
           (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))
 #else
 #  ifdef PNG_USER_CHUNK_MALLOC_MAX
-      if ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
+         || ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
           prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)
 #  endif
 #endif
+         )
          png_warning(png_ptr, "Exceeded size limit while expanding chunk");
 
       /* If the size is zero either there was an error and a message
@@ -448,12 +451,7 @@ png_decompress_chunk(png_structp png_ptr, int comp_type,
        * and we have nothing to do - the code will exit through the
        * error case below.
        */
-#if defined(PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED) || \
-    defined(PNG_USER_CHUNK_MALLOC_MAX)
       else if (expanded_size > 0)
-#else
-      if (expanded_size > 0)
-#endif
       {
          /* Success (maybe) - really uncompress the chunk. */
          png_size_t new_size = 0;
@@ -1279,7 +1277,7 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_free(png_ptr, png_ptr->chunkdata);
    png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
-   slength = (png_size_t)length;
+   slength = length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, skip))
@@ -1429,7 +1427,7 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
     * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
     * potential breakage point if the types in pngconf.h aren't exactly right.
     */
-   slength = (png_size_t)length;
+   slength = length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, skip))
@@ -1956,7 +1954,7 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   slength = (png_size_t)length;
+   slength = length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, 0))
@@ -2105,7 +2103,7 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   slength = (png_size_t)length;
+   slength = length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
    png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
@@ -2265,7 +2263,7 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
      return;
    }
 
-   slength = (png_size_t)length;
+   slength = length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, skip))
@@ -2373,7 +2371,7 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   slength = (png_size_t)length;
+   slength = length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, 0))
@@ -2504,7 +2502,7 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   slength = (png_size_t)length;
+   slength = length;
    png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, 0))
diff --git a/src/libpng/pngstruct.h b/src/libpng/pngstruct.h
index 07f3a0425..860b8bff8 100644
--- a/src/libpng/pngstruct.h
+++ b/src/libpng/pngstruct.h
@@ -5,7 +5,7 @@
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
- * Last changed in libpng 1.5.5 [September 22, 2011]
+ * Last changed in libpng 1.5.9 [February 18, 2012]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ -283,9 +283,7 @@ struct png_struct_def
 #endif
 
 /* New member added in libpng-1.0.4 (renamed in 1.0.9) */
-#if defined(PNG_MNG_FEATURES_SUPPORTED) || \
-    defined(PNG_READ_EMPTY_PLTE_SUPPORTED) || \
-    defined(PNG_WRITE_EMPTY_PLTE_SUPPORTED)
+#if defined(PNG_MNG_FEATURES_SUPPORTED)
 /* Changed from png_byte to png_uint_32 at version 1.2.0 */
    png_uint_32 mng_features_permitted;
 #endif