diff --git a/ChangeLog b/ChangeLog
index 492291dc19..d7569960e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Jun  8 23:56:00 2013  Tanaka Akira  <akr@fsij.org>
+
+	* numeric.c (rb_num_to_uint): Use rb_absint_size instead of
+	  RBIGNUM_LEN.
+
 Sat Jun  8 22:53:45 2013  Tanaka Akira  <akr@fsij.org>
 
 	* marshal.c (r_object0): Use rb_integer_unpack.
diff --git a/numeric.c b/numeric.c
index f675034e6c..5a15e5b82e 100644
--- a/numeric.c
+++ b/numeric.c
@@ -142,8 +142,7 @@ rb_num_to_uint(VALUE val, unsigned int *ret)
 	return NUMERR_TOOLARGE;
 #else
 	/* long is 32bit */
-#define DIGSPERLONG (SIZEOF_LONG/SIZEOF_BDIGITS)
-	if (RBIGNUM_LEN(val) > DIGSPERLONG) return NUMERR_TOOLARGE;
+	if (rb_absint_size(val, NULL) > sizeof(int)) return NUMERR_TOOLARGE;
 	*ret = (unsigned int)rb_big2ulong((VALUE)val);
 	return 0;
 #endif