diff --git a/Gemfile b/Gemfile
index d86fdf0..f9f35c0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ group :development, :test do
   gem "rake"
   gem "pry"
   gem "pry-rails"
-  gem "test-unit-rails", github: "test-unit/test-unit-rails"
+  gem "test-unit-rails", github: "test-unit/test-unit-rails", branch: "support-system-test-case"
   gem "test-unit-notify"
 end
 
diff --git a/Gemfile.lock b/Gemfile.lock
index a665108..759dab0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,3 +1,15 @@
+GIT
+  remote: git://github.com/test-unit/test-unit-rails.git
+  revision: 32adf391ed6e35b55bf21193f0c0556f4bcc7792
+  branch: support-system-test-case
+  specs:
+    test-unit-rails (5.1.4)
+      rails (>= 5.1.2)
+      test-unit (>= 3.1.7)
+      test-unit-activesupport (>= 1.0.8)
+      test-unit-capybara (>= 1.0.5)
+      test-unit-rr (>= 1.0.4)
+
 PATH
   remote: .
   specs:
@@ -343,12 +355,6 @@ GEM
       test-unit (>= 2.5.3)
     test-unit-notify (1.0.4)
       test-unit (>= 2.4.9)
-    test-unit-rails (5.1.3)
-      rails (>= 5.1.2)
-      test-unit (>= 3.1.7)
-      test-unit-activesupport (>= 1.0.8)
-      test-unit-capybara (>= 1.0.5)
-      test-unit-rr (>= 1.0.4)
     test-unit-rr (1.0.5)
       rr (>= 1.1.1)
       test-unit (>= 2.5.2)
@@ -399,7 +405,7 @@ DEPENDENCIES
   selenium-webdriver (~> 3.13.1)
   simplecov (~> 0.16.1)
   test-unit-notify
-  test-unit-rails
+  test-unit-rails!
   timecop
   web-console (~> 3.6)
   webmock (~> 3.3.0)