diff --git a/Dockerfile b/Dockerfile
index 763ec12..83976bf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.12 as builder
+FROM alpine:3.14 as builder
 
 RUN apk --no-cache add \
     rpcgen \
@@ -17,15 +17,15 @@ RUN apk --no-cache add \
     icu-dev \
     inotify-tools-dev
 
-ENV SHA256_SUM_DOVECOT=4784fb98dd41b83888e4aa9908efcbcad2e04a254e97440863903c0c498486f9
-ENV DOVECOT_FILENAME=dovecot-2.3.9.2.tar.gz
+ENV SHA256_SUM_DOVECOT=03a71d53055bd9ec528d55e07afaf15c09dec9856cba734904bfd05acbc6cf12
+ENV DOVECOT_FILENAME=dovecot-2.3.16.tar.gz
 RUN wget https://www.dovecot.org/releases/2.3/$DOVECOT_FILENAME
 RUN echo "$SHA256_SUM_DOVECOT  $DOVECOT_FILENAME" | sha256sum -c - || exit 1
 RUN mkdir /tmp/dovecot
 RUN tar xzf $DOVECOT_FILENAME -C /tmp/dovecot --strip 1
 
-ENV SHA256_SUM_PIGEONHOLE=36da68aae5157b83e21383f711b8977e5b6f5477f369f71e7e22e76a738bbd05
-ENV PIGEONHOLE_FILENAME=dovecot-2.3-pigeonhole-0.5.9.tar.gz
+ENV SHA256_SUM_PIGEONHOLE=5ca36780e23b99e6206440f1b3fe3c6598eda5b699b99cebb15d418ba3c6e938
+ENV PIGEONHOLE_FILENAME=dovecot-2.3-pigeonhole-0.5.16.tar.gz
 RUN wget https://pigeonhole.dovecot.org/releases/2.3/$PIGEONHOLE_FILENAME
 RUN echo "$SHA256_SUM_PIGEONHOLE  $PIGEONHOLE_FILENAME" | sha256sum -c - || exit 1
 RUN mkdir /tmp/pigeonhole