diff --git a/release.sh b/release.sh
index cdd8a84cfc664314526e5ef851c3777b473f8430..fc5a3871db1a0c7ef7671b3bdd847798251f47ad 100755
--- a/release.sh
+++ b/release.sh
@@ -4,7 +4,7 @@
 current=`grep -P "__version_info__ = \(\'\d+\', \'\d+\', \'\d+(\w*)\'\)" src/sakia/__init__.py | grep -oP "\'\d+\', \'\d+\', \'\d+(\w*)\'"`
 echo "Current version: $current"
 
-if [[ $1 =~ ^[0-9]+.[0-9]+.[0-9]+[0-9a-z]*$ ]]; then
+if [[ $1 =~ ^[0-9]+.[0-9]+.[0-9]+[0-9A-Za-z]*$ ]]; then
   IFS='.' read -r -a array <<< "$1"
   sed -i "s/__version_info__\ = ($current)/__version_info__ = ('${array[0]}', '${array[1]}', '${array[2]}')/g" src/sakia/__init__.py
   sed -i "s/#define MyAppVerStr .*/#define MyAppVerStr \"$1\"/g" ci/appveyor/sakia.iss