diff --git a/resources/js/pages/sites/Edit.vue b/resources/js/pages/sites/Edit.vue
index 9eb90a7edab..9c4f172688d 100644
--- a/resources/js/pages/sites/Edit.vue
+++ b/resources/js/pages/sites/Edit.vue
@@ -3,6 +3,7 @@ import Head from '@/pages/layout/Head.vue';
 import { Header, CommandPaletteItem, Button, PublishContainer, DocsCallout } from '@ui';
 import { computed, onMounted, onUnmounted, ref, useTemplateRef } from 'vue';
 import { Pipeline, Request } from '@ui/Publish/SavePipeline.js';
+import { clone } from '@/bootstrap/globals.js';
 
 const props = defineProps({
     blueprint: Object,
@@ -12,7 +13,7 @@ const props = defineProps({
 });
 
 const container = useTemplateRef('container');
-const values = ref(props.initialValues);
+const values = ref(clone(props.initialValues));
 const errors = ref({});
 const saving = ref(false);
 
diff --git a/resources/js/tests/pages/SitesEdit.test.js b/resources/js/tests/pages/SitesEdit.test.js
new file mode 100644
index 00000000000..463b48c56f0
--- /dev/null
+++ b/resources/js/tests/pages/SitesEdit.test.js
@@ -0,0 +1,57 @@
+import { mount } from '@vue/test-utils';
+import { afterEach, expect, test, vi } from 'vitest';
+import { data_set } from '@/bootstrap/globals';
+import Edit from '@/pages/sites/Edit.vue';
+
+let multisiteEnabled = false;
+
+globalThis.Statamic = {
+    $config: { get: (key) => (key === 'multisiteEnabled' ? multisiteEnabled : undefined) },
+    $keys: { bindGlobal: () => ({ destroy: () => {} }) },
+    $commandPalette: { add: () => {}, category: { Actions: 'Actions' } },
+};
+
+function mountEdit(initialValues) {
+    return mount(Edit, {
+        props: { blueprint: null, initialValues, meta: {}, updateUrl: '/update' },
+        global: {
+            stubs: {
+                Head: true,
+                Header: true,
+                CommandPaletteItem: true,
+                Button: true,
+                PublishContainer: true,
+                DocsCallout: true,
+            },
+            mocks: {
+                $commandPalette: { category: { Actions: 'Actions' } },
+            },
+        },
+    });
+}
+
+afterEach(() => {
+    multisiteEnabled = false;
+    vi.restoreAllMocks();
+});
+
+test('it warns before saving a changed site handle', () => {
+    const confirm = vi.spyOn(window, 'confirm').mockReturnValue(false);
+    const wrapper = mountEdit({ handle: 'default', name: 'Default' });
+
+    data_set(wrapper.vm.values, 'handle', 'main');
+    wrapper.vm.save();
+
+    expect(confirm).toHaveBeenCalledOnce();
+});
+
+test('it warns before saving a changed handle when multisite is enabled', () => {
+    multisiteEnabled = true;
+    const confirm = vi.spyOn(window, 'confirm').mockReturnValue(false);
+    const wrapper = mountEdit({ sites: [{ handle: 'default' }, { handle: 'french' }] });
+
+    data_set(wrapper.vm.values, 'sites.0.handle', 'english');
+    wrapper.vm.save();
+
+    expect(confirm).toHaveBeenCalledOnce();
+});