diff --git a/jjb/pipeline/voltha/master/physical-build.groovy b/jjb/pipeline/voltha/master/physical-build.groovy
index 47c9907..25cd2a0 100644
--- a/jjb/pipeline/voltha/master/physical-build.groovy
+++ b/jjb/pipeline/voltha/master/physical-build.groovy
@@ -113,7 +113,7 @@
             }
 
             // adding user specified helm flags at the end so they'll have priority over everything else
-            localHelmFlags = localHelmFlags += " ${extraHelmFlags}"
+            localHelmFlags = localHelmFlags + " ${extraHelmFlags}"
 
             volthaDeploy([
               workflow: workFlow.toLowerCase(),