diff --git a/ChangeLog b/ChangeLog
index 37c0a24b53..13c8592fe1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Nov 24 10:17:51 2006  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* bignum.c (bignorm): avoid segmentation.  a patch from Hiroyuki
+	  Ito <ZXB01226@nifty.com>.  [ruby-list:43012]
+
 Thu Nov 23 10:38:40 2006  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* eval.c (rb_mod_define_method): set implicit visibility only when
diff --git a/bignum.c b/bignum.c
index 552648c631..cc3dd1e5c3 100644
--- a/bignum.c
+++ b/bignum.c
@@ -99,7 +99,10 @@ static VALUE
 bignorm(x)
     VALUE x;
 {
-    if (!FIXNUM_P(x)) {
+    if (FIXNUM_P(x)) {
+      return x;
+    }
+    else if (TYPE(x) == T_BIGNUM) {
 	long len = RBIGNUM(x)->len;
 	BDIGIT *ds = BDIGITS(x);