diff --git a/.env b/.env
index 73a2458..ff137af 100644
--- a/.env
+++ b/.env
@@ -26,3 +26,6 @@ EMAIL_SERVER_HOST='smtp.example.com'
 EMAIL_SERVER_PORT=587
 EMAIL_SERVER_USER='email_user'
 EMAIL_SERVER_PASSWORD='email_password'
+
+# Encryption key that will be used to encrypt CalDAV credentials, choose a random string, for example with `dd if=/dev/urandom bs=1K count=1 | md5sum`
+CALENDSO_ENCRYPTION_KEY=''