diff --git a/Dockerfile b/Dockerfile
index 55a8900..341993e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,4 @@
-FROM alpine:3.12 as builder
-
-ENV RESTY_VERSION=1.15.8.2
-ENV RESTY_SHA256_SUM=436b4e84d547a97a18cf7a2522daf819da8087b188468946b5a89c0dd1ca5d16
+FROM alpine:3.14 as builder
 
 RUN apk --no-cache add \
     bash \
@@ -28,6 +25,9 @@ RUN apk --no-cache add \
 RUN ln -s /usr/bin/aclocal-1.16 /usr/bin/aclocal-1.15
 RUN ln -s /usr/bin/automake-1.16 /usr/bin/automake-1.15
 
+ENV RESTY_VERSION=1.19.3.2
+ENV RESTY_SHA256_SUM=ce40e764990fbbeb782e496eb63e214bf19b6f301a453d13f70c4f363d1e5bb9
+
 RUN wget https://openresty.org/download/openresty-$RESTY_VERSION.tar.gz
 RUN echo "$RESTY_SHA256_SUM openresty-$RESTY_VERSION.tar.gz" | sha256sum -c - || exit 1
 RUN tar xvf openresty-$RESTY_VERSION.tar.gz
@@ -38,13 +38,18 @@ RUN cd openresty-$RESTY_VERSION && \
 
 ADD gin.patch /gin.patch
 RUN git clone https://github.com/ostinelli/gin
+ENV GIN_VERSION=cb35e87fa0671fcf25e5bce5cb9487dee8b497e2
 
 WORKDIR /gin
+RUN git checkout "$GIN_VERSION"
 RUN patch -N -p1 < ../gin.patch
 RUN luarocks-5.1 make
 
 WORKDIR /
 RUN git clone https://github.com/koreader/koreader-sync-server.git
+ENV SYNC_VERSION=d7d1ebff54240cfbade96a81f2971b6ad0afa33f
+WORKDIR /koreader-sync-server
+RUN git checkout "$SYNC_VERSION"
 
 FROM thallian/confd-env:latest
 
@@ -77,3 +82,4 @@ WORKDIR /
 
 EXPOSE 7200
 VOLUME /var/lib/redis/
+