diff --git a/.ruby-version b/.ruby-version
new file mode 100644
index 0000000000..55bc9834c3
--- /dev/null
+++ b/.ruby-version
@@ -0,0 +1 @@
+ruby-2.4.1
diff --git a/circle.yml b/circle.yml
index 681dc7e410..b03d664d0f 100644
--- a/circle.yml
+++ b/circle.yml
@@ -4,10 +4,6 @@ dependencies:
   post:
     - bundle exec appraisal install
 
-machine:
-  ruby:
-    version: 2.3.1
-
 test:
   pre:
     - cp .sample.env .env