diff --git a/README.md b/README.md
index 7014ea3..ff1186d 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ TLS certs are obtained via lets encrypt
 
 ## Extremely useful documentation
 
-- http://www.postfix.org/documentation.html
+- https://www.postfix.org/documentation.html
 
 - https://doc.dovecot.org/2.4.2/