diff --git a/Dockerfile b/Dockerfile
index 54dbc1d..463250d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
-FROM ruby:2.6.6-alpine3.11
+FROM ruby:2.6.6-alpine3.12
 
-ARG VERSION=v3.1.4
+ARG VERSION=v3.1.5
 ARG REPOSITORY=tootsuite/mastodon
 ARG LIBICONV_VERSION=1.15