diff --git a/roles/service/defaults/main.yml b/roles/service/defaults/main.yml
index db82c97..047aab8 100644
--- a/roles/service/defaults/main.yml
+++ b/roles/service/defaults/main.yml
@@ -7,6 +7,7 @@ docker_restart_policy: always
 
 reverse_proxy_type: caddy
 docker_proxy_target_protocol: http
+docker_vhost_additional_locations: []
 
 docker_additional_env: {}
 docker_additional_services: []
diff --git a/roles/service/meta/argument_specs.yml b/roles/service/meta/argument_specs.yml
index 232f173..a142f7c 100644
--- a/roles/service/meta/argument_specs.yml
+++ b/roles/service/meta/argument_specs.yml
@@ -171,6 +171,7 @@ argument_specs:
       docker_vhost_additional_locations:
         description: "Passed to vhost role as vhost_locations variable"
         required: false
+        default: []
       docker_published_ports:
         description: "A list of published ports in docker format (<host listen address>:<host port>:<container port>)"
         type: list