diff --git a/Dockerfile b/Dockerfile
index 0635a101..a8df46c6 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,14 +1,16 @@
 FROM golang:alpine3.9 as builder
 
 RUN apk --update upgrade \
-&& apk --no-cache --no-progress add make git \
-&& rm -rf /var/cache/apk/*
+    && apk --no-cache --no-progress add make git
 
 WORKDIR /go/src/github.com/go-acme/lego
 COPY . .
 RUN make build
 
 FROM alpine:3.9
-RUN apk update && apk add --no-cache --virtual ca-certificates
+RUN apk update \
+    && apk add --no-cache ca-certificates tzdata \
+    && update-ca-certificates
+
 COPY --from=builder /go/src/github.com/go-acme/lego/dist/lego /usr/bin/lego
 ENTRYPOINT [ "/usr/bin/lego" ]