From 6ad0a0bd70147cd784813e955a85f1c90de19b2d Mon Sep 17 00:00:00 2001
From: tgotic <tgotic@sourceforge.net>
Date: Mon, 16 May 2011 20:04:56 +0200
Subject: [PATCH] =?UTF-8?q?ISBN-13=20check=20digit=20now=20correctly=20ide?=
 =?UTF-8?q?ntifies=20'0'.=20Thanks=20to=20K=C3=A9vin=20Sailly.?=
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---
 backend/upcean.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/backend/upcean.c b/backend/upcean.c
index f9a6c989..cf60733f 100644
--- a/backend/upcean.c
+++ b/backend/upcean.c
@@ -376,8 +376,8 @@ char isbn13_check(unsigned char source[]) /* For ISBN(13) only */
 		if(weight == 1) weight = 3; else weight = 1;
 	}
 
-	check = sum % 10;
-	check = 10 - check;
+	check = (10 - (sum % 10))  % 10;
+
 	return itoc(check);
 }