diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 3d73f711a9..d834c89171 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -36,7 +36,7 @@ jobs:
         id: gen_vars
         run: |
           repo_url="https://github.com/${{ env.GITHUB_REPOSITORY }}.git"
-          build_num=$(${{ env.GITHUB_RUN_NUMBER }} + 3000) 
+          build_num=$(expr ${{ env.GITHUB_RUN_NUMBER }} + 3000) 
 
           echo "::set-output name=repo_url::$repo_url" 
           echo "::set-output name=adj_build_number::$build_num"