diff --git a/lib/generators/shopify_app/install/install_generator.rb b/lib/generators/shopify_app/install/install_generator.rb
index 1bce6ee9d..24482170f 100644
--- a/lib/generators/shopify_app/install/install_generator.rb
+++ b/lib/generators/shopify_app/install/install_generator.rb
@@ -67,7 +67,7 @@ def mount_engine
       def insert_hosts_into_development_config
         inject_into_file(
           'config/environments/development.rb',
-          "  config.hosts = (config.hosts rescue []) << /\\w+\\.ngrok\\.io/\n",
+          "  config.hosts = (config.hosts rescue []) << /\[-\w]+\\.ngrok\\.io/\n",
           after: "Rails.application.configure do\n"
         )
       end
diff --git a/test/generators/install_generator_test.rb b/test/generators/install_generator_test.rb
index e491c25f8..2dcfc6812 100644
--- a/test/generators/install_generator_test.rb
+++ b/test/generators/install_generator_test.rb
@@ -98,7 +98,7 @@ class InstallGeneratorTest < Rails::Generators::TestCase
   test "adds host config to development.rb" do
     run_generator
     assert_file "config/environments/development.rb" do |config|
-      assert_match "config.hosts = (config.hosts rescue []) << /\\w+\\.ngrok\\.io/", config
+      assert_match "config.hosts = (config.hosts rescue []) << /\[-\w]+\\.ngrok\\.io/", config
     end
   end