diff --git a/roles/ipsilon/templates/ipsilon.conf b/roles/ipsilon/templates/ipsilon.conf
index 6245a83748..4685cb71ff 100644
--- a/roles/ipsilon/templates/ipsilon.conf
+++ b/roles/ipsilon/templates/ipsilon.conf
@@ -16,6 +16,7 @@ tools.sessions.storage_dburi = "postgresql://{{ ipsilon_db_user }}:{{ ipsilon_db
 tools.sessions.timeout = 15
 tools.sessions.httponly = True
 tools.sessions.secure = True
+tools.sessions.locking = 'explicit'
 
 tools.proxy.on = True
 {% if env == 'staging' %}