diff --git a/ansible/roles/apps/templates/settings/prometheus-stack.yaml b/ansible/roles/apps/templates/settings/prometheus-stack.yaml
index c791e4917933823cae021f73e7e0260cc54d0b09..1f43815ef8636c7a78cae10034266bbb980db940 100644
--- a/ansible/roles/apps/templates/settings/prometheus-stack.yaml
+++ b/ansible/roles/apps/templates/settings/prometheus-stack.yaml
@@ -45,7 +45,7 @@ alertmanager:
       {% if outgoing_mail.enabled %}
       receiver: email
       {% else %}
-      receiver: null
+      receiver: 'null'
       {% endif %}
       routes:
       - match: