diff --git a/ChangeLog b/ChangeLog
index af01055e5b..8e864015b6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Tue Jun 25 19:07:33 2013  Tanaka Akira  <akr@fsij.org>
+
+	* bignum.c (LSHIFTX): Revert r41611.
+	  The redundant expression suppresses a warning, C4293, by Visual
+	  Studio.
+	  http://ruby-mswin.cloudapp.net/vc10-x64/ruby-trunk/log/20130625T072854Z.log.html.gz#miniruby
+
 Tue Jun 25 19:03:00 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (big2ulong): Add a cast.
diff --git a/bignum.c b/bignum.c
index 78fd02fb7a..f9cd368dee 100644
--- a/bignum.c
+++ b/bignum.c
@@ -39,7 +39,8 @@ static VALUE big_three = Qnil;
 #   define HOST_BIGENDIAN_P 0
 #endif
 #define ALIGNOF(type) ((int)offsetof(struct { char f1; type f2; }, f2))
-#define LSHIFTX(d, n) (sizeof(d) * CHAR_BIT <= (n) ? 0 : ((d) << (n)))
+/* (sizeof(d) * CHAR_BIT <= (n) ? 0 : (n)) is same as n but suppress a warning, C4293, by Visual Studio.  */
+#define LSHIFTX(d, n) (sizeof(d) * CHAR_BIT <= (n) ? 0 : ((d) << (sizeof(d) * CHAR_BIT <= (n) ? 0 : (n))))
 #define CLEAR_LOWBITS(d, numbits) ((d) & LSHIFTX(~((d)*0), (numbits)))
 #define FILL_LOWBITS(d, numbits) ((d) | (LSHIFTX(((d)*0+1), (numbits))-1))