diff --git a/README.md b/README.md
index 8fc1e612459d560e701c47499b461288ce5898c0..42ff3dd7355ddbd47072b00f1277075be447d7d2 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ your choice.
  2. Get the ip address of the new VM, and configure your ssh environment
  3. Create & activate a python virtual environment and install ansible
  4. Update inventory.yml so that your VM is defined in the "gitlab-runner" group
- 5. Create the file `group_vars/ci-runners.yml` following the [example file](group_vars/ci-runners.yml.example) given
+ 5. Create the file `group_vars/ci_runners.yml` following the [example file](group_vars/ci_runners.yml.example) given
     * Consider the type of executor you want/need (docker, shell, etc.)
         * More info on GitLab runner executors can be found [here](https://docs.gitlab.com/runner/executors/)
     * This requires acquiring an access token to the GitLab instance for which you want to set up a runner
diff --git a/group_vars/ci-runners.yml.example b/group_vars/ci_runners.yml.example
similarity index 100%
rename from group_vars/ci-runners.yml.example
rename to group_vars/ci_runners.yml.example
diff --git a/inventory.yml b/inventory.yml
index 2b6b69057e2056991256dde39df6c63d68654e9f..93131c69b730b16a8cd3325fd52cfc083ccdd60f 100644
--- a/inventory.yml
+++ b/inventory.yml
@@ -1,4 +1,4 @@
-ci-runners:
+ci_runners:
   hosts:
     nat-runner-01:
       ansible_host: nat-runner-01
diff --git a/playbook.yml b/playbook.yml
index ffe8d2e3b3f34efcc5d5230cddd72dd06c66e49a..deb61e67ee0b6ae948e0eec2f97ad7e7734f2e75 100644
--- a/playbook.yml
+++ b/playbook.yml
@@ -1,5 +1,5 @@
 - name: Install and set up a GitLab CI runner
-  hosts: ci-runners
+  hosts: ci_runners
   become: true
   roles:
     - gitlab-runner
diff --git a/roles/gitlab-runner/tasks/main.yml b/roles/gitlab-runner/tasks/main.yml
index 997fbf9650f1b9d1f6d925e340614214c554ceb6..b3d3991c51a46712e71144d785c73938979188fc 100644
--- a/roles/gitlab-runner/tasks/main.yml
+++ b/roles/gitlab-runner/tasks/main.yml
@@ -42,6 +42,7 @@
       - '--url={{ runner.gitlab_url }}'
       - '--token={{ gitlab_authentication_response.runner.token }}'
       - '--executor={{ runner.executor }}'
+      - '--docker-image=alpine:latest'
       - '--non-interactive'
   become: true
   no_log: true