diff --git a/ANNOUNCE b/ANNOUNCE
index 45c778212..7cd1cc877 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.6.0beta20 - March 21, 2012
+Libpng 1.6.0beta20 - March 22, 2012
 
 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.
@@ -339,10 +339,11 @@ Version 1.6.0beta19 [March 18,2012]
   Avoid the double gamma correction warning in the simplified API.
     This allows the --strict option to pass in the pngstest checks
 
-Version 1.6.0beta20 [March 21, 2012]
+Version 1.6.0beta20 [March 22, 2012]
   Changed chunk handler warnings into benign errors, incrementally load iCCP
   Recognize known sRGB ICC profiles while reading and handle them as if the
     sRGB chunk had appeared instead.
+  Added checksum-icc.c to contrib/libtests
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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diff --git a/CHANGES b/CHANGES
index b00dc8959..b8a585743 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4090,10 +4090,11 @@ Version 1.6.0beta19 [March 18, 2012]
   Avoid the double gamma correction warning in the simplified API.
     This allows the --strict option to pass in the pngstest checks
 
-Version 1.6.0beta20 [March 21, 2012]
+Version 1.6.0beta20 [March 22, 2012]
   Changed chunk handler warnings into benign errors, incrementally load iCCP
   Recognize known sRGB ICC profiles while reading and handle them as if the
     sRGB chunk had appeared instead.
+  Added checksum-icc.c to contrib/libtests
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/contrib/libtests/checksum-icc.c b/contrib/libtests/checksum-icc.c
new file mode 100644
index 000000000..85b387946
--- /dev/null
+++ b/contrib/libtests/checksum-icc.c
@@ -0,0 +1,89 @@
+/* checksum-icc.c
+ *
+ * Copyright (c) 2012 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.0 [(PENDING RELEASE)]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Generate crc32 and adler32 checksums of the given input files, used to
+ * generate check-codes for use when matching ICC profiles within libpng.
+ */
+#include <stdio.h>
+
+#include <zlib.h>
+
+static int
+read_one_file(FILE *ip, const char *name)
+{
+   uLong length = 0;
+   uLong a32 = adler32(0, NULL, 0);
+   uLong c32 = crc32(0, NULL, 0);
+
+   for (;;)
+   {
+      int ch = getc(ip);
+      Byte b;
+
+      if (ch == EOF) break;
+
+      b = (Byte)ch;
+
+      ++length;
+      a32 = adler32(a32, &b, 1);
+      c32 = crc32(c32, &b, 1);
+   }
+
+   if (ferror(ip))
+      return 0;
+
+   /* Success */
+   printf("{ 0x%8.8lx, 0x%8.8lx, %lu, \"%s\" },\n", (unsigned long)a32,
+      (unsigned long)c32, (unsigned long)length, name);
+
+   return 1;
+}
+
+int main(int argc, char **argv)
+{
+   int err = 0;
+
+   printf("= { /* adler32   crc32   length  name */\n");
+
+   if (argc > 1)
+   {
+      int i;
+
+      for (i=1; i<argc; ++i)
+      {
+         FILE *ip = fopen(argv[i], "rb");
+
+         if (ip == NULL || !read_one_file(ip, argv[i]))
+         {
+            err = 1;
+            perror(argv[i]);
+            fprintf(stderr, "%s: read error\n", argv[i]);
+            printf(" { 0, 0, 0, /* ERROR: */, \"%s\" },\n", argv[i]);
+         }
+
+         (void)fclose(ip);
+      }
+   }
+
+   else
+   {
+      if (!read_one_file(stdin, "-"))
+      {
+         err = 1;
+         perror("stdin");
+         fprintf(stderr, "stdin: read error\n");
+         printf(" { 0, 0, 0, /* ERROR: */, \"-\" },\n");
+      }
+   }
+
+   printf("};\n");
+
+   return err;
+}