diff --git a/ChangeLog b/ChangeLog
index 9c4836d61a..0b1f453c3c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Jun 22 13:47:13 2013  Tanaka Akira  <akr@fsij.org>
+
+	* bignum.c (bary_pack): MEMZERO can be used even if nails is not zero.
+
 Sat Jun 22 13:43:00 2013  Charlie Somerville  <charliesome@ruby-lang.org>
 
 	* ext/etc/etc.c (etc_getpwnam): use PRIsVALUE in format string instead
diff --git a/bignum.c b/bignum.c
index 7c78a3fbd8..0b2b6ef1ed 100644
--- a/bignum.c
+++ b/bignum.c
@@ -919,7 +919,7 @@ bary_pack(int sign, BDIGIT *ds, size_t num_bdigits, void *words, size_t numwords
         sign = 0;
     }
 
-    if (nails == 0 && sign == 0) {
+    if (sign == 0) {
         MEMZERO(words, unsigned char, numwords * wordsize);
         return 0;
     }