diff --git a/ChangeLog b/ChangeLog
index 82b6fd960a..ad79809812 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Feb 22 19:50:19 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* bignum.c (BIGZEROP): fix for longer Bignum zeros.  [ruby-Bugs-17454]
+
 Fri Feb 22 15:47:36 2008  Tanaka Akira  <akr@fsij.org>
 
 	* encoding.c (rb_enc_mbclen): return minlen instead of 1 when
diff --git a/bignum.c b/bignum.c
index 2119b7d9aa..7220b80a36 100644
--- a/bignum.c
+++ b/bignum.c
@@ -36,7 +36,19 @@ VALUE rb_cBignum;
 #define BIGLO(x) ((BDIGIT)((x) & (BIGRAD-1)))
 #define BDIGMAX ((BDIGIT)-1)
 
-#define BIGZEROP(x) (RBIGNUM_LEN(x) == 0 || (RBIGNUM_LEN(x) == 1 && BDIGITS(x)[0] == 0))
+#define BIGZEROP(x) (RBIGNUM_LEN(x) == 0 || \
+		     (BDIGITS(x)[0] == 0 && \
+		      (RBIGNUM_LEN(x) == 1 || bigzero_p(x))))
+
+static int
+bigzero_p(VALUE x)
+{
+    long i;
+    for (i = 0; i < RBIGNUM_LEN(x); ++i) {
+	if (BDIGITS(x)[i]) return 0;
+    }
+    return 1;
+}
 
 #define RBIGNUM_SET_LEN(b,l) \
   ((RBASIC(b)->flags & RBIGNUM_EMBED_FLAG) ? \