diff --git a/playbooks/groups/libravatar.yml b/playbooks/groups/libravatar.yml
index eb0dd37e01..ca593fd217 100644
--- a/playbooks/groups/libravatar.yml
+++ b/playbooks/groups/libravatar.yml
@@ -34,4 +34,4 @@
   roles:
    - base
    - libravatar
-   - { role: letsencrypt, site_name: {{ inventory_hostname }} }
+   - { role: letsencrypt, site_name: "{{ inventory_hostname }}" }