diff --git a/installer/local_docker/tasks/standalone.yml b/installer/local_docker/tasks/standalone.yml
index 3c5fd29a60..3e377157d5 100644
--- a/installer/local_docker/tasks/standalone.yml
+++ b/installer/local_docker/tasks/standalone.yml
@@ -81,7 +81,7 @@
     image: "{{ awx_web_docker_actual_image }}"
     volumes: >
       {{
-        [project_data_dir + ':/var/lib/awx/projects:rw' if project_data_dir is defined else []
+        [project_data_dir + ':/var/lib/awx/projects:rw'] if project_data_dir is defined else []
         + [ca_trust_dir + ':/etc/pki/ca-trust:ro'] if ca_trust_dir is defined else []
       }}
     user: root
@@ -119,7 +119,7 @@
     image: "{{ awx_task_docker_actual_image }}"
     volumes: >
       {{
-        [project_data_dir + ':/var/lib/awx/projects:rw' if project_data_dir is defined else []
+        [project_data_dir + ':/var/lib/awx/projects:rw'] if project_data_dir is defined else []
         + [ca_trust_dir + ':/etc/pki/ca-trust:ro'] if ca_trust_dir is defined else []
       }}
     links: "{{ awx_task_container_links|list }}"