diff --git a/jobs/pipelines/swarm-create-cfg-config-drive.groovy b/jobs/pipelines/swarm-create-cfg-config-drive.groovy
index 72d278f..46d5010 100644
--- a/jobs/pipelines/swarm-create-cfg-config-drive.groovy
+++ b/jobs/pipelines/swarm-create-cfg-config-drive.groovy
@@ -152,7 +152,10 @@
 
     stage("Set data"){
         for (i in entries(smc)) {
-            sh "sed -i \"s,export ${i[0]}=.*,export ${i[0]}=${i[1]},\" ${user_data_script_path}"
+            // Replace only if the variable is non-empty, leave default otherwise
+            if (i[1]) {
+                sh "sed -i \"s,export ${i[0]}=.*,export ${i[0]}=${i[1]},\" ${user_data_script_path}"
+            }
         }
     }