diff --git a/Dockerfile b/Dockerfile
index b1588a1..185b2fc 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.8 as builder
+FROM alpine:3.9 as builder
 
 RUN apk --no-cache add \
     rpcgen \
@@ -96,4 +96,3 @@ EXPOSE 143 4190 6334 7777
 VOLUME /var/lib/vmail/mail/ /etc/ssl/mail
 
 ADD /rootfs /
-