diff --git a/ANNOUNCE b/ANNOUNCE
index a857a388a..5b6c36624 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.15beta01 - October 23, 2014
+Libpng 1.6.15beta01 - October 25, 2014
 
 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.
@@ -25,7 +25,8 @@ Other information:
 
 Changes since the last public release (1.6.14):
 
-Version 1.6.15beta01 [October 23, 2014]
+Version 1.6.15beta01 [October 25, 2014]
+  Changed "if (!x)" to "if (x == 0)" and "if (x)" to "if (x !== 0)"
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 6e37c2178..3358981f9 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5033,7 +5033,8 @@ Version 1.6.14rc02 [October 17, 2014]
 Version 1.6.14 [October 23, 2014]
   No changes.
 
-Version 1.6.15beta01 [October 23, 2014]
+Version 1.6.15beta01 [October 25, 2014]
+  Changed "if (!x)" to "if (x == 0)" and "if (x)" to "if (x !== 0)"
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/png.c b/png.c
index 1ff36a51a..52b7e13a6 100644
--- a/png.c
+++ b/png.c
@@ -1,7 +1,7 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.6.14 [October 23, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
  * Copyright (c) 1998-2014 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.)
@@ -773,13 +773,13 @@ png_get_copyright(png_const_structrp png_ptr)
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-     "libpng version 1.6.15beta01 - October 23, 2014" PNG_STRING_NEWLINE \
+     "libpng version 1.6.15beta01 - October 25, 2014" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2014 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 1.6.15beta01 - October 23, 2014\
+      return "libpng version 1.6.15beta01 - October 25, 2014\
       Copyright (c) 1998-2014 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -3277,7 +3277,8 @@ png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
                result = -result;
 
             /* Check for overflow. */
-            if ((negative && result <= 0) || (!negative && result >= 0))
+            if ((negative != 0 && result <= 0) ||
+                (negative == 0 && result >= 0))
             {
                *res = result;
                return 1;
diff --git a/pngrutil.c b/pngrutil.c
index a48907aeb..bfc855941 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.6.14 [October 23, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
  * Copyright (c) 1998-2014 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.)
@@ -2643,10 +2643,10 @@ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
        */
       ++prefix_length;
 
-      if (!compressed && prefix_length <= length)
+      if (compressed == 0 && prefix_length <= length)
          uncompressed_length = length - prefix_length;
 
-      else if (compressed && prefix_length < length)
+      else if (compressed != 0 && prefix_length < length)
       {
          uncompressed_length = PNG_SIZE_MAX;
 
@@ -2954,7 +2954,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
 #endif /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
 
    /* Check for unhandled critical chunks */
-   if (!handled && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
+   if (handled == 0 && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
       png_chunk_error(png_ptr, "unhandled critical chunk");
 }
 
diff --git a/pngtest.c b/pngtest.c
index aac8aba71..9e7e76574 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -1,7 +1,7 @@
 
 /* pngtest.c - a simple test program to test libpng
  *
- * Last changed in libpng 1.6.11 [June 5, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
  * Copyright (c) 1998-2014 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.)
@@ -1780,10 +1780,11 @@ main(int argc, char *argv[])
       }
    }
 
-   if (!multiple && argc == 3 + verbose)
+   if (multiple == 0 && argc == 3 + verbose)
      outname = argv[2 + verbose];
 
-   if ((!multiple && argc > 3 + verbose) || (multiple && argc < 2))
+   if ((multiple == 0 && argc > 3 + verbose) ||
+       (multiple != 0 && argc < 2))
    {
      fprintf(STDERR,
        "usage: %s [infile.png] [outfile.png]\n\t%s -m {infile.png}\n",
diff --git a/pngwrite.c b/pngwrite.c
index 6a831f62c..6aae6c326 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -1,7 +1,7 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.6.14 [October 23, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
  * Copyright (c) 1998-2014 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.)
@@ -2135,9 +2135,11 @@ png_image_write_main(png_voidp argument)
    png_uint_32 format = image->format;
 
    int colormap = (format & PNG_FORMAT_FLAG_COLORMAP) != 0;
-   int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR) != 0; /* input */
-   int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA) != 0;
-   int write_16bit = linear && !colormap && !display->convert_to_8bit;
+   /* input */
+   int linear = (colormap == 0) && (format & PNG_FORMAT_FLAG_LINEAR) != 0;
+   int alpha = (colormap == 0) && (format & PNG_FORMAT_FLAG_ALPHA) != 0;
+   int write_16bit = (linear != 0 ) && (colormap == 0) &&
+       (display->convert_to_8bit == 0);
 
 #  ifdef PNG_BENIGN_ERRORS_SUPPORTED
       /* Make sure we error out on any bad situation */
@@ -2224,7 +2226,7 @@ png_image_write_main(png_voidp argument)
 #  ifdef PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
       if (format & PNG_FORMAT_FLAG_BGR)
       {
-         if (!colormap && (format & PNG_FORMAT_FLAG_COLOR) != 0)
+         if (colormap == 0 && (format & PNG_FORMAT_FLAG_COLOR) != 0)
             png_set_bgr(png_ptr);
          format &= ~PNG_FORMAT_FLAG_BGR;
       }
@@ -2233,7 +2235,7 @@ png_image_write_main(png_voidp argument)
 #  ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
       if (format & PNG_FORMAT_FLAG_AFIRST)
       {
-         if (!colormap && (format & PNG_FORMAT_FLAG_ALPHA) != 0)
+         if (colormap == 0 && (format & PNG_FORMAT_FLAG_ALPHA) != 0)
             png_set_swap_alpha(png_ptr);
          format &= ~PNG_FORMAT_FLAG_AFIRST;
       }
@@ -2280,7 +2282,8 @@ png_image_write_main(png_voidp argument)
     * before it is written.  This only applies when the input is 16-bit and
     * either there is an alpha channel or it is converted to 8-bit.
     */
-   if ((linear && alpha) || (!colormap && display->convert_to_8bit))
+   if ((linear != 0 && alpha != 0 ) ||
+       (colormap == 0 && display->convert_to_8bit != 0))
    {
       png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr,
          png_get_rowbytes(png_ptr, info_ptr)));