diff --git a/spec/acceptance_spec_helper.rb b/spec/acceptance_spec_helper.rb
index f9150bfe..b0730b9b 100644
--- a/spec/acceptance_spec_helper.rb
+++ b/spec/acceptance_spec_helper.rb
@@ -1,3 +1,9 @@
+require_relative 'support/tests/current_bundle'
+
+Tests::CurrentBundle.instance.assert_appraisal!
+
+#---
+
 require 'rspec/core'
 
 Dir[ File.join(File.expand_path('../support/acceptance/**/*.rb', __FILE__)) ].sort.each do |file|
diff --git a/spec/support/tests/current_bundle.rb b/spec/support/tests/current_bundle.rb
new file mode 100644
index 00000000..d5039a44
--- /dev/null
+++ b/spec/support/tests/current_bundle.rb
@@ -0,0 +1,47 @@
+require 'bundler'
+require 'appraisal'
+
+module Tests
+  class CurrentBundle
+    AppraisalNotSpecified = Class.new(ArgumentError)
+
+    include Singleton
+
+    def assert_appraisal!
+      unless appraisal?
+        message = <<EOT
+
+
+Please run tests starting with `appraisal <appraisal_name>`.
+Possible appraisals are: #{possible_appraisals}
+
+EOT
+        raise AppraisalNotSpecified, message
+      end
+    end
+
+    private
+
+    def possible_appraisals
+      appraisals = []
+
+      Appraisal::File.each do |appraisal|
+        appraisals << appraisal.name
+      end
+
+      appraisals
+    end
+
+    def path
+      Bundler.default_gemfile
+    end
+
+    def appraisal?
+      path.dirname == root.join('gemfiles')
+    end
+
+    def root
+      Pathname.new('../../../..').expand_path(__FILE__)
+    end
+  end
+end
diff --git a/spec/unit_spec_helper.rb b/spec/unit_spec_helper.rb
index 5806eb3f..fd000746 100644
--- a/spec/unit_spec_helper.rb
+++ b/spec/unit_spec_helper.rb
@@ -1,3 +1,9 @@
+require_relative 'support/tests/current_bundle'
+
+Tests::CurrentBundle.instance.assert_appraisal!
+
+#---
+
 require File.expand_path('../support/unit/rails_application', __FILE__)
 
 def monkey_patch_minitest_to_do_nothing