diff --git a/spec/issues/730_swagger_is_not_detecting_mounted_rack_app.rb b/spec/issues/730_swagger_is_not_detecting_mounted_rack_app.rb
new file mode 100644
index 00000000..cf6fd5e6
--- /dev/null
+++ b/spec/issues/730_swagger_is_not_detecting_mounted_rack_app.rb
@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+require 'grape-swagger/entity'
+
+module API
+  module V1
+    class Welcome < Grape::API
+      desc 'Greets user' do
+        detail 'This is the root api and it will greet user on accessing'
+      end
+      get '/' do
+        {
+          data: [
+            { message: 'Welcome to notes app' }
+          ]
+        }
+      end
+    end
+  end
+end
+
+module API
+  module V1
+    class Base < Grape::API
+      version :v1, using: :path
+
+      mount Welcome
+    end
+  end
+end
+
+module API
+  class Base < Grape::API
+    format :json
+    prefix :api
+
+    mount V1::Base
+
+    add_swagger_documentation hide_documentation_path: true,
+                              version: 'V1',
+                              info: {
+                                title: 'User notes app',
+                                description: 'Demo app for user notes'
+                              }
+  end
+end
+
+describe 'swagger is not detecting mounted rack app' do
+  let(:app) { API::Base }
+
+  context 'when a rack app is mounted under API::Base' do
+    context 'when api/v1/ is called' do
+      subject do
+        get '/api/v1'
+        JSON.parse(last_response.body)
+      end
+
+      it 'checks if the response is correct' do
+        expect(subject).to eq('data' => [{ 'message' => 'Welcome to notes app' }])
+      end
+    end
+
+    context 'when api/swagger_doc is called' do
+      subject do
+        get '/api/swagger_doc'
+        JSON.parse(last_response.body)
+      end
+
+      it 'checks if the swagger documentation is properly generated' do
+        expect(subject['paths']).to_not be_nil
+      end
+    end
+  end
+end