diff --git a/CHANGELOG b/CHANGELOG
index c6398b08..f3ddd7e8 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -11,6 +11,7 @@
 	- remove obsolete iati2hxl endpoint
 	- improve organisation and documentation for controllers
 	- added more controller unit tests
+	- change Dockerfile tag for the base Python image
 
 2019-04-04 Release 1.15.1
 	- fix caching for validation requests sent via POST
diff --git a/Dockerfile b/Dockerfile
index b5967824..5f5d2156 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM unocha/alpine-base-s6-python3:latest
+FROM unocha/alpine-base-s6-python3:3.8
 
 WORKDIR /srv/www