diff --git a/README.md b/README.md
index f2def1aa..31c66781 100644
--- a/README.md
+++ b/README.md
@@ -237,6 +237,7 @@ To use Redis for memory caching as well as PHP session storage, specify the foll
 - `REDIS_HOST` (not set by default) Name of Redis container
 - `REDIS_HOST_PORT` (default: `6379`) Optional port for Redis, only use for external Redis servers that run on non-standard ports.
 - `REDIS_HOST_PASSWORD` (not set by default) Redis password
+- `REDIS_PROTOCOL` (default: `tcp`) Set to `tls` to use TLS when connecting to Redis server
 
 Check the [Nextcloud documentation](https://docs.nextcloud.com/server/latest/admin_manual/configuration_server/caching_configuration.html) for more information.