diff --git a/ChangeLog b/ChangeLog
index 12e0016319..a5b0d13281 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Tue Jun 25 12:42:57 2013  Tanaka Akira  <akr@fsij.org>
+
+	* bignum.c (integer_unpack_single_bdigit): Use "1 + ~u" instead of
+	  "-u" to suppress warning (C4146) by Visual Studio.
+	  Reported by ko1 via IRC.
+
 Tue Jun 25 12:28:57 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (big2ulong): Add code specialized for SIZEOF_LONG <=
diff --git a/bignum.c b/bignum.c
index 697d833299..53a9ad5c8a 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1351,7 +1351,7 @@ integer_unpack_single_bdigit(BDIGIT u, size_t size, int flags, BDIGIT *dp)
             ((u >> (size * CHAR_BIT - 1)) ? -1 : 1);
         if (sign < 0) {
             u |= LSHIFTX(BDIGMAX, size * CHAR_BIT);
-            u = BIGLO(-u);
+            u = BIGLO(1 + ~u);
         }
     }
     else