diff --git a/build b/build
index 46cd60bc9..684057bf1 100755
--- a/build
+++ b/build
@@ -65,7 +65,7 @@ make_relup() {
     if [ -d "$releases_dir" ]; then
         while read -r zip; do
             local base_vsn
-            base_vsn="$(echo "$zip" | grep -oE "[0-9]+\.[0-9]+\.[0-9]+(-[0-9a-e]{8})?")"
+            base_vsn="$(echo "$zip" | grep -oE "[0-9]+\.[0-9]+\.[0-9]+(-[0-9a-f]{8})?")"
             if [ ! -d "$releases_dir/$base_vsn" ]; then
                 local tmp_dir
                 tmp_dir="$(mktemp -d -t emqx.XXXXXXX)"