diff --git a/circle.yml b/circle.yml
new file mode 100644
index 0000000..cf0bc81
--- /dev/null
+++ b/circle.yml
@@ -0,0 +1,3 @@
+checkout:
+  post:
+    - mkdir -p tmp
diff --git a/spec/models/plugin_spec.rb b/spec/models/plugin_spec.rb
index e16dd3b..02a2316 100644
--- a/spec/models/plugin_spec.rb
+++ b/spec/models/plugin_spec.rb
@@ -4,7 +4,7 @@ describe Plugin do
   let(:plugin) { FactoryGirl.build(:plugin) }
 
   before do
-    Plugin.stub(:gemfile_path).and_return { "/tmp/fluentd-ui-test-gemfile.plugins" } # NOTE: can't create a file under Rails.root directory on Circle CI
+    Plugin.stub(:gemfile_path).and_return { Rails.root + "tmp/fluentd-ui-test-gemfile.plugins" }
   end
 
   after do