Index: include/ruby/ruby.h
===================================================================
--- include/ruby/ruby.h.orig	2011-10-26 23:47:14.150402377 +0000
+++ include/ruby/ruby.h	2011-10-26 23:49:18.012257670 +0000
@@ -256,19 +256,19 @@
 # define SSIZET2NUM(v) INT2NUM(v)
 #endif
 
-#ifndef SSIZE_MAX
+#ifndef SIZE_MAX
 # if SIZEOF_SIZE_T > SIZEOF_LONG && defined(HAVE_LONG_LONG)
-#   define SSIZE_MAX LLONG_MAX
-#   define SSIZE_MIN LLONG_MIN
+#   define SIZE_MAX ULLONG_MAX
+#   define SIZE_MIN ULLONG_MIN
 # elif SIZEOF_SIZE_T == SIZEOF_LONG
-#   define SSIZE_MAX LONG_MAX
-#   define SSIZE_MIN LONG_MIN
+#   define SIZE_MAX ULONG_MAX
+#   define SIZE_MIN ULONG_MIN
 # elif SIZEOF_SIZE_T == SIZEOF_INT
-#   define SSIZE_MAX INT_MAX
-#   define SSIZE_MIN INT_MIN
+#   define SIZE_MAX UINT_MAX
+#   define SIZE_MIN UINT_MIN
 # else
-#   define SSIZE_MAX SHRT_MAX
-#   define SSIZE_MIN SHRT_MIN
+#   define SIZE_MAX USHRT_MAX
+#   define SIZE_MIN USHRT_MIN
 # endif
 #endif