diff --git a/CHANGELOG.md b/CHANGELOG.md
index a2e783f8..40d07b0f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 * Added `GrapeEntity::VERSION` - [@dblock](https://github.com/dblock).
 * Added Rubocop, Ruby-style linter - [@dblock](https://github.com/dblock).
 * [#126](https://github.com/tim-vandecasteele/grape-swagger/pull/126): Rewritten demo in the `test` folder with CORS enabled - [@dblock](https://github.com/dblock).
+* [#127](https://github.com/tim-vandecasteele/grape-swagger/pull/127): Fixed `undefined method 'reject' for nil:NilClass` error for an invalid route, now returning 404 Not Found - [@dblock](https://github.com/dblock).
 * Your Contribution Here
 
 ### 0.7.2 (February 6, 2014)
diff --git a/lib/grape-swagger.rb b/lib/grape-swagger.rb
index c208e14d..6e20d546 100644
--- a/lib/grape-swagger.rb
+++ b/lib/grape-swagger.rb
@@ -131,11 +131,14 @@ def self.setup(options)
 
               models = []
               routes = target_class.combined_routes[params[:name]]
+              error!('Not Found', 404) unless routes
 
               ops = routes.reject(&:route_hidden).group_by do |route|
                 parse_path(route.route_path, api_version)
               end
 
+              error!('Not Found', 404) unless ops.any?
+
               apis = []
 
               ops.each do |path, op_routes|
diff --git a/spec/non_default_api_spec.rb b/spec/non_default_api_spec.rb
index f7bcd896..ee74789a 100644
--- a/spec/non_default_api_spec.rb
+++ b/spec/non_default_api_spec.rb
@@ -634,4 +634,29 @@ def app
       expect(ret['apis'][0]['operations'][0]['nickname']).to eq 'getSomething'
     end
   end
+
+  context 'invalid name' do
+    subject do
+      Class.new(Grape::API) do
+        get 'hidden', hidden: true
+        add_swagger_documentation
+      end
+    end
+
+    def app
+      subject
+    end
+
+    it 'returns a 404 for an non-existent route' do
+      get '/swagger_doc/invalid.json'
+      expect(last_response.status).to eq 404
+      expect(JSON.parse(last_response.body)).to eq('error' => 'Not Found')
+    end
+
+    it 'returns a 404 for a hidden route' do
+      get '/swagger_doc/hidden.json'
+      expect(last_response.status).to eq 404
+      expect(JSON.parse(last_response.body)).to eq('error' => 'Not Found')
+    end
+  end
 end