diff --git a/lib/generators/devise/install_generator.rb b/lib/generators/devise/install_generator.rb
index d3eabbea..2717d2aa 100644
--- a/lib/generators/devise/install_generator.rb
+++ b/lib/generators/devise/install_generator.rb
@@ -10,6 +10,7 @@ module Devise
       class_option :orm
 
       def copy_initializer
+        raise "An ORM must be set to install Devise" unless options[:orm]
         template "devise.rb", "config/initializers/devise.rb"
       end
 
diff --git a/test/generators/install_generator_test.rb b/test/generators/install_generator_test.rb
index db63e23a..6a4657e1 100644
--- a/test/generators/install_generator_test.rb
+++ b/test/generators/install_generator_test.rb
@@ -6,8 +6,16 @@ class InstallGeneratorTest < Rails::Generators::TestCase
   setup :prepare_destination
 
   test "Assert all files are properly created" do
-    run_generator
-    assert_file "config/initializers/devise.rb"
+    run_generator(['--orm=active_record'])
+    assert_file "config/initializers/devise.rb", /devise\/orm\/active_record/
     assert_file "config/locales/devise.en.yml"
   end
+
+  test "Fail if no ORM is specified" do
+    error = assert_raises RuntimeError do
+      run_generator
+    end
+
+    assert_match /An ORM must be set to install Devise/, error.message
+  end
 end