diff --git a/.gitea/workflows/build.yml b/.gitea/workflows/build.yml
index 49260a7..69a1568 100644
--- a/.gitea/workflows/build.yml
+++ b/.gitea/workflows/build.yml
@@ -27,7 +27,7 @@ jobs:
           if [ tag = "main" ]; then
             tag="latest"
           else
-            tag_num=$tag + "-" + $tag_num
+            tag_num="${tag}-${tag_num}"
           fi
 
           docker build -t hnshosting-master:$tag_num .