diff --git a/mitmproxy/version.py b/mitmproxy/version.py
index 9b0fb2b51..7b90d4ee1 100644
--- a/mitmproxy/version.py
+++ b/mitmproxy/version.py
@@ -2,7 +2,7 @@ import os
 import subprocess
 import sys
 
-VERSION = "5.3.0"
+VERSION = "6.0.0.dev"
 PATHOD = "pathod " + VERSION
 MITMPROXY = "mitmproxy " + VERSION
 
diff --git a/release/docker/Dockerfile b/release/docker/Dockerfile
index 5f496e9f9..0e9ef3fd0 100644
--- a/release/docker/Dockerfile
+++ b/release/docker/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.11
+FROM alpine:3.12
 
 ENV LANG=en_US.UTF-8