diff --git a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2 b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
index 08476c259..d41313e39 100644
--- a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
+++ b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
@@ -968,7 +968,7 @@ account_validity:
 #  - email
 #  - msisdn
 {% if matrix_synapse_registrations_require_3pid|length > 0 %}
-registrations_require_3pid: {{ matrix_synapse_registrations_require_3pid|to_nice_yaml }}
+registrations_require_3pid: {{ matrix_synapse_registrations_require_3pid|to_json }}
 {% endif %}
 
 # Explicitly disable asking for MSISDNs from the registration
@@ -987,7 +987,7 @@ registrations_require_3pid: {{ matrix_synapse_registrations_require_3pid|to_nice
 #  - medium: msisdn
 #    pattern: '\+44'
 {% if matrix_synapse_allowed_local_3pids|length > 0 %}
-allowed_local_3pids: {{ matrix_synapse_allowed_local_3pids|to_nice_yaml }}
+allowed_local_3pids: {{ matrix_synapse_allowed_local_3pids|to_json }}
 {% endif %}
 
 # Enable 3PIDs lookup requests to identity servers from this server.