diff --git a/salt/elasticsearch/config.map.jinja b/salt/elasticsearch/config.map.jinja
index b9ddaa988..9a80ce30f 100644
--- a/salt/elasticsearch/config.map.jinja
+++ b/salt/elasticsearch/config.map.jinja
@@ -10,7 +10,7 @@
     {% if salt['pillar.get']('nodestab', {}) %}
       {% do ESCONFIG.elasticsearch.config.node.update({'roles': ['master', 'data', 'remote_cluster_client']}) %}
       {% if HIGHLANDER %}
-          {% do ESCONFIG.elasticsearch.config.node.roles.append('ml', 'transform') %}
+          {% do ESCONFIG.elasticsearch.config.node.roles.extend(['ml', 'transform']) %}
       {% endif %}
       {% do ESCONFIG.elasticsearch.config.update({'discovery': {'seed_hosts': [grains.master]}}) %}
       {% for SN, SNDATA in salt['pillar.get']('nodestab', {}).items() %}