diff --git a/5.1/Containerfile b/5.1/Containerfile
index 0890e95..3af403e 100644
--- a/5.1/Containerfile
+++ b/5.1/Containerfile
@@ -1,4 +1,4 @@
-FROM docker.io/redmine:6.0
+FROM docker.io/redmine:5.1
 
 RUN apt-get -qy update && apt-get -qy upgrade && apt-get -qy install git libffi-dev make gcc nodejs graphviz