diff --git a/lib/generators/trestle/auth/install/install_generator.rb b/lib/generators/trestle/auth/install/install_generator.rb
index 750febd..d87e38a 100644
--- a/lib/generators/trestle/auth/install/install_generator.rb
+++ b/lib/generators/trestle/auth/install/install_generator.rb
@@ -18,7 +18,7 @@ def check_trestle_installed
         end
 
         def insert_configuration
-          inject_into_file "config/initializers/trestle.rb", before: /^end/ do
+          inject_into_file "config/initializers/trestle.rb", before: /end(?!.*end.*)/m do
             format_configuration(template_content(configuration_template))
           end
         end
diff --git a/spec/generators/install_generator_spec.rb b/spec/generators/install_generator_spec.rb
index 4bb0511..e4f3066 100644
--- a/spec/generators/install_generator_spec.rb
+++ b/spec/generators/install_generator_spec.rb
@@ -132,4 +132,29 @@
       end
     end
   end
+
+  context "when the existing Trestle configuration is improperly indented" do
+    let(:configuration) do
+      <<~EOF
+        Trestle.configure do |config|
+        config.menu do
+        end
+          end
+      EOF
+    end
+
+    describe "the generated files" do
+      before do
+        run_generator generator_params
+      end
+
+      describe "the Trestle configuration" do
+        subject { file("config/initializers/trestle.rb") }
+
+        it { is_expected.to have_correct_syntax }
+        it { is_expected.to contain "# == Authentication Options" }
+        it { is_expected.not_to contain /config.menu do\n\s*# == Authentication Options/ }
+      end
+    end
+  end
 end