diff --git a/README_SETUP.md b/README_SETUP.md
index d237200bb068f78928e6058bb0c4462f7ce95c0b..d8ec5188e291cba44f354b6ee57c099e11f86627 100644
--- a/README_SETUP.md
+++ b/README_SETUP.md
@@ -59,6 +59,9 @@ you need to uncomment the respective sections in `envoy.yml` and `docker-compose
 The given configuration assumes, that the certificate files are placed in a folder
 `compose/certs` and named `caosdb.key.pem` and `caosdb.cert.pem`.
 
+It is assumed, that `caosdb.key.pem` does not have a passphrase. You can remove one
+with `openssl rsa -in oldKey.pem -out newKey.key`.
+
 
 ## Configuration
 ### Bind IP