diff --git a/.github/workflows/auto_build.yml b/.github/workflows/auto_build.yml
index fc4088b..189ef7e 100644
--- a/.github/workflows/auto_build.yml
+++ b/.github/workflows/auto_build.yml
@@ -73,7 +73,7 @@ jobs:
                 core.info(`\u001b[35mtag_updated: ${tag_updated}, latest_upstream_tag_name: ${latest_upstream_tag_name}, current_tag_name: ${current_tag_name}`);
                 // Exporting variables
                 // see also 
-                core.exportVariable('tag_updated', tag_updated);
+                core.exportVariable('tag_updated', `${tag_updated}`);
                 core.exportVariable('latest_upstream_tag_name', latest_upstream_tag_name);
                 core.exportVariable('current_tag_name', current_tag_name);
                 // invoke build action if tag_updated