From c0b257db2577494d96a7e2ffc2418d0392f5ae5f Mon Sep 17 00:00:00 2001
From: Alex Shinn <ashinn@users.noreply.github.com>
Date: Mon, 31 Dec 2012 10:51:42 +0900
Subject: [PATCH] Fixing overflow checking in certain cases in bignum addition.
 (patch from Lorenzo)

---
 bignum.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bignum.c b/bignum.c
index 9dcbf936..3f513822 100644
--- a/bignum.c
+++ b/bignum.c
@@ -344,7 +344,7 @@ sexp sexp_bignum_add_digits (sexp ctx, sexp dst, sexp a, sexp b) {
     carry = (n > (SEXP_UINT_T_MAX - bdata[i]) ? 1 : 0);
   }
   for ( ; carry && (i<alen); i++) {
-    carry = (cdata[i] == SEXP_UINT_T_MAX-1 ? 1 : 0);
+    carry = (cdata[i] == SEXP_UINT_T_MAX ? 1 : 0);
     cdata[i]++;
   }
   if (carry) {