diff --git a/roles/matrix-synapse/defaults/main.yml b/roles/matrix-synapse/defaults/main.yml
index ef585e37e..50301d5b0 100644
--- a/roles/matrix-synapse/defaults/main.yml
+++ b/roles/matrix-synapse/defaults/main.yml
@@ -286,3 +286,5 @@ matrix_synapse_room_list_publication_rules:
     alias: "*"
     room_id: "*"
     action: allow
+
+matrix_synapse_default_room_version: "4"
diff --git a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2 b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
index 6f3213bea..869f313f5 100644
--- a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
+++ b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
@@ -82,7 +82,7 @@ use_presence: {{ matrix_synapse_use_presence|to_json }}
 # For example, for room version 1, default_room_version should be set
 # to "1".
 #
-#default_room_version: "4"
+default_room_version: "{{ matrix_synapse_default_room_version|to_json }}"
 
 # The GC threshold parameters to pass to `gc.set_threshold`, if defined
 #