diff --git a/2.1/onbuild/Dockerfile b/2.1/onbuild/Dockerfile
index 9a9bdb7b6b..4fa6874c8e 100644
--- a/2.1/onbuild/Dockerfile
+++ b/2.1/onbuild/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:2.1
+FROM ruby:2.7.6
 
 # throw errors if Gemfile has been modified since Gemfile.lock
 RUN bundle config --global frozen 1