diff --git a/ANNOUNCE b/ANNOUNCE
index 1c54af490..debc98585 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.5.0beta56 - November 25, 2010
+Libpng 1.5.0beta56 - December 5, 2010
 
 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.
@@ -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 [November 25, 2010]
+version 1.5.0beta25 [December 5, 2010]
   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
 
@@ -451,7 +451,8 @@ Version 1.5.0beta55 [November 21, 2010]
     with pngwio.c and pngwutil.c because the 'write' callback and zlib
     compression both fail to declare their input buffers with 'const'.
 
-Version 1.5.0beta56 [November 25, 2010]
+Version 1.5.0beta56 [December 5, 2010]
+  Added the private PNG_UNUSED() macro definition in pngpriv.h.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net:
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 617e9331d..bc55f6e63 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3089,7 +3089,8 @@ Version 1.5.0beta55 [November 21, 2010]
     with pngwio.c and pngwutil.c because the 'write' callback and zlib
     compression both fail to declare their input buffers with 'const'.
 
-Version 1.5.0beta56 [November 25, 2010]
+Version 1.5.0beta56 [December 5, 2010]
+  Added the private PNG_UNUSED() macro definition in pngpriv.h.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/png.c b/png.c
index 9b00f79f3..046173b48 100644
--- a/png.c
+++ b/png.c
@@ -550,19 +550,19 @@ png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime)
 png_const_charp PNGAPI
 png_get_copyright(png_structp png_ptr)
 {
-   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
+   PNG_UNUSED(png_ptr)  /* Silence compiler warning about unused png_ptr */
 #ifdef PNG_STRING_COPYRIGHT
-      return PNG_STRING_COPYRIGHT
+   return PNG_STRING_COPYRIGHT
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-     "libpng version 1.5.0beta56 - November 25, 2010" PNG_STRING_NEWLINE \
+     "libpng version 1.5.0beta56 - December 5, 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 "libpng version 1.5.0beta56 - November 25, 2010\
+      return "libpng version 1.5.0beta56 - December 5, 2010\
       Copyright (c) 1998-2010 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -589,7 +589,7 @@ png_const_charp PNGAPI
 png_get_header_ver(png_structp png_ptr)
 {
    /* Version of *.h files used when building libpng */
-   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
+   PNG_UNUSED(png_ptr)  /* Silence compiler warning about unused png_ptr */
    return PNG_LIBPNG_VER_STRING;
 }
 
@@ -597,7 +597,7 @@ png_const_charp PNGAPI
 png_get_header_version(png_structp png_ptr)
 {
    /* Returns longer string containing both version and date */
-   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
+   PNG_UNUSED(png_ptr)  /* Silence compiler warning about unused png_ptr */
 #ifdef __STDC__
    return PNG_HEADER_VERSION_STRING
 #  ifndef PNG_READ_SUPPORTED
diff --git a/pngerror.c b/pngerror.c
index 3fc724218..dac371d43 100644
--- a/pngerror.c
+++ b/pngerror.c
@@ -322,7 +322,7 @@ png_default_error,(png_structp png_ptr, png_const_charp error_message),
    }
 #endif
 #ifndef PNG_CONSOLE_IO_SUPPORTED
-   error_message = error_message; /* Make compiler happy */
+   PNG_UNUSED(error_message) /* Make compiler happy */
 #endif
    png_longjmp(png_ptr, 1);
 }
@@ -394,9 +394,9 @@ png_default_warning(png_structp png_ptr, png_const_charp warning_message)
       fprintf(stderr, PNG_STRING_NEWLINE);
    }
 #else
-   warning_message = warning_message; /* Make compiler happy */
+   PNG_UNUSED(warning_message) /* Make compiler happy */
 #endif
-   png_ptr = png_ptr; /* Make compiler happy */
+   PNG_UNUSED(png_ptr) /* Make compiler happy */
 }
 #endif /* PNG_WARNINGS_SUPPORTED */
 
diff --git a/pngpread.c b/pngpread.c
index c893104b5..9af1b67ea 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -1230,7 +1230,7 @@ png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
 {
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
       {
-         info_ptr = info_ptr; /* To quiet some compiler warnings */
+         PNG_UNUSED(info_ptr) /* To quiet some compiler warnings */
          png_error(png_ptr, "Out of place tEXt");
          /*NOT REACHED*/
       }
@@ -1327,7 +1327,7 @@ png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
 {
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
    {
-      info_ptr = info_ptr; /* To quiet some compiler warnings */
+      PNG_UNUSED(info_ptr) /* To quiet some compiler warnings */
       png_error(png_ptr, "Out of place zTXt");
       /*NOT REACHED*/
    }
@@ -1531,7 +1531,7 @@ png_push_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
 {
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
    {
-      info_ptr = info_ptr; /* To quiet some compiler warnings */
+      PNG_UNUSED(info_ptr) /* To quiet some compiler warnings */
       png_error(png_ptr, "Out of place iTXt");
       /*NOT REACHED*/
    }
@@ -1669,7 +1669,7 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
 #endif
          png_chunk_error(png_ptr, "unknown critical chunk");
 
-      info_ptr = info_ptr; /* To quiet some compiler warnings */
+      PNG_UNUSED(info_ptr) /* To quiet some compiler warnings */
    }
 
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
diff --git a/pngpriv.h b/pngpriv.h
index 87a89e316..2fa26f495 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -81,6 +81,15 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #  define PNG_MAX_MALLOC_64K
 #endif
 
+/* Unused formal parameter errors are removed using the following macro
+ * which is expected to have no bad effects on performance.  Note that
+ * if you replace it with something other than whitespace, you must include
+ * the terminating semicolon.
+ */
+#ifndef PNG_UNUSED
+#  define PNG_UNUSED(param) param = param;
+#endif
+
 /* Just a little check that someone hasn't tried to define something
  * contradictory.
  */
diff --git a/pngread.c b/pngread.c
index 30605d1bd..223321717 100644
--- a/pngread.c
+++ b/pngread.c
@@ -1457,8 +1457,8 @@ png_read_png(png_structp png_ptr, png_infop info_ptr,
    /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
    png_read_end(png_ptr, info_ptr);
 
-   transforms = transforms; /* Quiet compiler warnings */
-   params = params;
+   PNG_UNUSED(transforms)   /* Quiet compiler warnings */
+   PNG_UNUSED(params)
 
 }
 #endif /* PNG_INFO_IMAGE_SUPPORTED */
diff --git a/pngrutil.c b/pngrutil.c
index 38464d2dd..6ff9a1e49 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -781,7 +781,7 @@ png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_crc_finish(png_ptr, length);
 
-   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
+   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
 }
 
 #ifdef PNG_READ_gAMA_SUPPORTED
@@ -2619,7 +2619,7 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_crc_finish(png_ptr, skip);
 
 #ifndef PNG_READ_USER_CHUNKS_SUPPORTED
-   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
+   PNG_UNUSED(info_ptr) /* Quiet compiler warnings about unused info_ptr */
 #endif
 }
 
@@ -3110,7 +3110,7 @@ png_do_read_interlace(png_structp png_ptr)
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
    }
 #ifndef PNG_READ_PACKSWAP_SUPPORTED
-   transformations = transformations; /* Silence compiler warning */
+   PNG_UNUSED(transformations)  /* Silence compiler warning */
 #endif
 }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
diff --git a/pngtest.c b/pngtest.c
index 03775f3b4..42c9352c0 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -425,7 +425,7 @@ static void PNGCBAPI
 pngtest_flush(png_structp png_ptr)
 {
    /* Do nothing; fflush() is said to be just a waste of energy. */
-   png_ptr = png_ptr;  /* Stifle compiler warning */
+   PNG_UNUSED(png_ptr)   /* Stifle compiler warning */
 }
 #endif
 
diff --git a/pngvalid.c b/pngvalid.c
index d1201e4a3..aa9207b9e 100644
--- a/pngvalid.c
+++ b/pngvalid.c
@@ -618,8 +618,7 @@ store_write(png_structp pp, png_bytep pb, png_size_t st)
 static void
 store_flush(png_structp pp)
 {
-   pp = pp;
-   /*DOES NOTHING*/
+   UNUSED(pp) /*DOES NOTHING*/
 }
 
 static size_t
diff --git a/pngwrite.c b/pngwrite.c
index 8fc8d450a..97645e0e7 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -1597,8 +1597,8 @@ png_write_png(png_structp png_ptr, png_infop info_ptr,
    /* It is REQUIRED to call this to finish writing the rest of the file */
    png_write_end(png_ptr, info_ptr);
 
-   transforms = transforms; /* Quiet compiler warnings */
-   params = params;
+   PNG_UNUSED(transforms)   /* Quiet compiler warnings */
+   PNG_UNUSED(params)
 }
 #endif
 #endif /* PNG_WRITE_SUPPORTED */