diff --git a/ChangeLog b/ChangeLog
index d66794d125..99f52cfea1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Jun 18 12:25:16 2013  Tanaka Akira  <akr@fsij.org>
+
+	* bignum.c (rb_big_xor): Non-effective code removed.
+
 Tue Jun 18 11:26:05 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* gc.c (gc_stat): add `generated_normal_object_count_types' for
diff --git a/bignum.c b/bignum.c
index 7eda823baf..dbe1a3353b 100644
--- a/bignum.c
+++ b/bignum.c
@@ -4638,8 +4638,6 @@ rb_big_xor(VALUE xx, VALUE yy)
 	ds2 = BDIGITS(y);
 	sign = RBIGNUM_SIGN(x);
     }
-    RBIGNUM_SET_SIGN(x, RBIGNUM_SIGN(x)?1:0);
-    RBIGNUM_SET_SIGN(y, RBIGNUM_SIGN(y)?1:0);
     z = bignew(l2, !(RBIGNUM_SIGN(x) ^ RBIGNUM_SIGN(y)));
     zds = BDIGITS(z);