diff --git a/Dockerfile b/Dockerfile
index 4f93f05..c4e0b77 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM boky/postfix
+FROM boky/postfix:v3.0.0
 LABEL org.opencontainers.image.source https://github.com/dbca-wa/docker-postfix-mailrelay
 
 ADD postmaps.sh /docker-init.db/