diff --git a/update.sh b/update.sh
index 08286cfd..d8b32ed8 100755
--- a/update.sh
+++ b/update.sh
@@ -9,7 +9,7 @@ set -e
 shopt -s extglob
 pushd `dirname $0` > /dev/null
 
-backupBundleFileName="backup-`date +%d-%m-%Y-%H-%M-%S`.tgz"
+backupBundleFileName="backup_`date +%Y-%m-%d_%H-%M-%S`.tgz"
 echo Making a backup of the current installation in ./data/backups/$backupBundleFileName
 mkdir -p ./data/backups > /dev/null
 touch ./data/backups/$backupBundleFileName