diff --git a/lib/rspec/rails/adapters.rb b/lib/rspec/rails/adapters.rb
index fc1a071bec..6ee7a8419e 100644
--- a/lib/rspec/rails/adapters.rb
+++ b/lib/rspec/rails/adapters.rb
@@ -14,6 +14,12 @@ module Rails
       # Constant aliased to either Minitest or TestUnit, depending on what is
       # loaded.
       Assertions = Minitest::Assertions
+    elsif RUBY_VERSION >= '2.2.0'
+      # Minitest has been removed from ruby core. However, we must be on an
+      # old Rails version and must load the Minitest 4.x gem
+      gem 'minitest' if defined?(Kernel.gem)
+      require 'minitest/unit'
+      Assertions = MiniTest::Assertions
     else
       begin
         require 'test/unit/assertions'