diff --git a/README.me b/README.me
index eb939b4..37cac9b 100644
--- a/README.me
+++ b/README.me
@@ -1,2 +1,2 @@
 # sslmate
-Docker container that syncs certificates from sslmate. Requires the `SSLMATE_API_KEY` environment variable to be set
+Docker container that syncs certificates from sslmate. Requires the `SSLMATE_API_KEY` environment variable to be set or 'SSLMATE_API_KEY_FILE' to use a secret.