diff --git a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2 b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
index 59c35c1fb..08476c259 100644
--- a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
+++ b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
@@ -967,8 +967,8 @@ account_validity:
 #registrations_require_3pid:
 #  - email
 #  - msisdn
-{% if matrix_synapse_registrations_require_3pid %}
-registrations_require_3pid: {{ matrix_synapse_registrations_require_3pid|to_json }}
+{% if matrix_synapse_registrations_require_3pid|length > 0 %}
+registrations_require_3pid: {{ matrix_synapse_registrations_require_3pid|to_nice_yaml }}
 {% endif %}
 
 # Explicitly disable asking for MSISDNs from the registration
@@ -986,8 +986,8 @@ registrations_require_3pid: {{ matrix_synapse_registrations_require_3pid|to_json
 #    pattern: '.*@vector\.im'
 #  - medium: msisdn
 #    pattern: '\+44'
-{% if matrix_synapse_allowed_local_3pids %}
-allowed_local_3pids: {{ matrix_synapse_allowed_local_3pids|to_json }}
+{% if matrix_synapse_allowed_local_3pids|length > 0 %}
+allowed_local_3pids: {{ matrix_synapse_allowed_local_3pids|to_nice_yaml }}
 {% endif %}
 
 # Enable 3PIDs lookup requests to identity servers from this server.