diff --git a/tasks/config.yaml b/tasks/config.yaml
index 39152c7..939075c 100644
--- a/tasks/config.yaml
+++ b/tasks/config.yaml
@@ -26,7 +26,9 @@
       when: consul_ssl
 
 - name: Merge config for Consul agent
-  when: inventory_hostname in groups[consul_agent_group]
+  when:
+    - groups[consul_agent_group] is defined
+    - inventory_hostname in groups[consul_agent_group]
   block:
     - name: Merge config for Consul agent
       set_fact: