diff --git a/instances/models.py b/instances/models.py
index 9248037a..3295bd59 100644
--- a/instances/models.py
+++ b/instances/models.py
@@ -6,12 +6,11 @@ from django.utils.translation import gettext_lazy as _
 from libvirt import (
     VIR_DOMAIN_SNAPSHOT_LIST_EXTERNAL,
     VIR_DOMAIN_SNAPSHOT_LIST_INTERNAL,
-    VIR_DOMAIN_XML_SECURE,
     libvirtError,
 )
 from operations import claims
 from operations.models import Claim
-from vrtManager.instance import wvmInstance
+from vrtManager.instance import PERSISTENT_XML, wvmInstance
 from webvirtcloud.settings import QEMU_CONSOLE_LISTENER_ADDRESSES
 
 
@@ -291,7 +290,8 @@ class Instance(models.Model):
 
     @cached_property
     def inst_xml(self):
-        return self.proxy._XMLDesc(VIR_DOMAIN_XML_SECURE)
+        # the definition for the next start, which is the current one while the VM is off
+        return self.proxy._XMLDesc(PERSISTENT_XML)
 
     @cached_property
     def has_managed_save_image(self):
diff --git a/instances/templates/instances/settings_tab.html b/instances/templates/instances/settings_tab.html
index 2ab07c9f..1b2ec0e4 100644
--- a/instances/templates/instances/settings_tab.html
+++ b/instances/templates/instances/settings_tab.html
@@ -656,46 +656,38 @@
         </div>
         <div role="tabpanel" class="tab-pane tab-pane-bordered" id="xmledit">
             {% if instance.status != 5 %}
-                <p>{% trans "If you need to edit XML please Power Off the instance" %}</p>
+                <p id="xml-next-start">{% trans "This is the definition for the VM's next start; a saved change applies then." %}</p>
             {% endif %}
             <form action="{% url 'instances:change_xml' instance.id %}" method="post" role="form" aria-label="Edit instance XML form" id="xml-form">
                 {% csrf_token %}
                 <div class="col-sm-12 xmlheight">
                     <textarea id="editor">{{ instance.inst_xml }}</textarea>
                 </div>
-                {% if instance.status == 5 %}
-                    <button type="submit" class="btn btn-lg btn-success float-end" name="change_xml">
-                        {% trans "Change" %}
-                    </button>
-                {% else %}
-                    <button class="btn btn-lg btn-success float-end disabled" disabled>
-                        {% trans "Change" %}
-                    </button>
-                {% endif %}
+                <button type="submit" class="btn btn-lg btn-success float-end" name="change_xml">
+                    {% trans "Change" %}
+                </button>
             </form>
             <div class="clearfix"></div>
-            {% if instance.status == 5 %}
-                <div class="modal fade" id="xml-review" tabindex="-1" aria-labelledby="xml-review-title" aria-hidden="true"
-                     data-failed="{% trans "The XML could not be checked. Try again." %}">
-                    <div class="modal-dialog modal-xl modal-dialog-scrollable">
-                        <div class="modal-content">
-                            <div class="modal-header">
-                                <h5 class="modal-title" id="xml-review-title">{% trans "Review the XML change" %}</h5>
-                                <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="{% trans "Close" %}"></button>
-                            </div>
-                            <div class="modal-body">
-                                <div class="alert alert-danger d-none" role="alert" id="xml-review-error"></div>
-                                <p class="d-none" id="xml-review-same">{% trans "The XML is the same as the VM's definition; there is nothing to save." %}</p>
-                                <pre class="d-none mb-0" id="xml-review-diff"></pre>
-                            </div>
-                            <div class="modal-footer">
-                                <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">{% trans "Cancel" %}</button>
-                                <button type="button" class="btn btn-success" id="xml-review-save">{% trans "Save" %}</button>
-                            </div>
+            <div class="modal fade" id="xml-review" tabindex="-1" aria-labelledby="xml-review-title" aria-hidden="true"
+                 data-failed="{% trans "The XML could not be checked. Try again." %}">
+                <div class="modal-dialog modal-xl modal-dialog-scrollable">
+                    <div class="modal-content">
+                        <div class="modal-header">
+                            <h5 class="modal-title" id="xml-review-title">{% trans "Review the XML change" %}</h5>
+                            <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="{% trans "Close" %}"></button>
+                        </div>
+                        <div class="modal-body">
+                            <div class="alert alert-danger d-none" role="alert" id="xml-review-error"></div>
+                            <p class="d-none" id="xml-review-same">{% trans "The XML is the same as the VM's definition; there is nothing to save." %}</p>
+                            <pre class="d-none mb-0" id="xml-review-diff"></pre>
+                        </div>
+                        <div class="modal-footer">
+                            <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">{% trans "Cancel" %}</button>
+                            <button type="button" class="btn btn-success" id="xml-review-save">{% trans "Save" %}</button>
                         </div>
                     </div>
                 </div>
-            {% endif %}
+            </div>
         </div>
         <div role="tabpanel" class="tab-pane tab-pane-bordered" id="users">
             <div>
diff --git a/instances/tests/test_change_xml.py b/instances/tests/test_change_xml.py
index 9faaee08..058d0d82 100644
--- a/instances/tests/test_change_xml.py
+++ b/instances/tests/test_change_xml.py
@@ -7,15 +7,18 @@ from django.test import TestCase
 from django.urls import reverse
 from instances.models import Instance
 from libvirt import libvirtError
+from vrtManager.instance import PERSISTENT_XML
 from logs.models import Logs
 
 CURRENT = "<domain>\n  <name>xml-vm</name>\n  <memory>1024</memory>\n</domain>"
+LIVE = "<domain id='3'>\n  <name>xml-vm</name>\n  <memory>512</memory>\n</domain>"
 EDITED = "<domain>\n  <name>xml-vm</name>\n  <memory>2048</memory>\n</domain>"
 
 
 class ChangeXmlTestCase(TestCase):
     """The XML editor shows what a change does before it is saved, and saves
-    only over the definition it was opened with."""
+    only over the definition it was opened with: the persistent one, which a
+    running VM uses at its next start."""
 
     def setUp(self):
         self.client.force_login(get_user_model().objects.create_superuser("xml_admin", "x@example.com", "pw"))
@@ -28,7 +31,7 @@ class ChangeXmlTestCase(TestCase):
             data["confirm"] = "1"
         with patch("instances.models.wvmInstance") as wvm:
             wvm.return_value.get_status.return_value = status
-            wvm.return_value._XMLDesc.return_value = CURRENT
+            wvm.return_value._XMLDesc.side_effect = lambda flags: CURRENT if flags == PERSISTENT_XML else LIVE
             wvm.return_value._defineXML.side_effect = define_error
             response = self.client.post(reverse("instances:change_xml", args=[self.instance.id]), data)
         return response, wvm.return_value._defineXML
@@ -67,13 +70,12 @@ class ChangeXmlTestCase(TestCase):
         row = Logs.objects.get(instance_uuid=self.instance.uuid)
         self.assertEqual((row.message, row.success), ("VM xml-vm: change XML: unsupported configuration: bad memory", False))
 
-    def test_running_or_paused_vm_is_refused(self):
+    def test_a_running_or_paused_vm_gets_the_definition_for_its_next_start(self):
         for status in (1, 3):
             with self.subTest(status=status):
                 response, define = self.post(status, confirm=True)
-                define.assert_not_called()
-                self.assertEqual(response.status_code, 409)
-                self.assertIn("Power off", response.json()["error"])
+                define.assert_called_once_with(EDITED)
+                self.assertIn("next start", " ".join(str(m) for m in get_messages(response.wsgi_request)))
 
     def test_the_line_breaks_a_form_posts_are_the_same_definition(self):
         response, _ = self.post(base=CURRENT.replace("\n", "\r\n"))
diff --git a/instances/tests/test_pending_edits.py b/instances/tests/test_pending_edits.py
index 2c54a02e..77612ef3 100644
--- a/instances/tests/test_pending_edits.py
+++ b/instances/tests/test_pending_edits.py
@@ -96,22 +96,25 @@ class PendingEditsTestCase(TestCase):
         self.assertEqual(doc.xpath("//select[@name='cur_vcpu']/option[@selected]/@value"), ["3"])
 
     def test_buttons_shown_as_disabled_cannot_submit(self):
-        # running: the CPU, options, video and XML forms wait for a shutdown
+        # running: the CPU, options and video forms wait for a shutdown
         doc = self.page(live=[disk("vda", "default", "")], config=[disk("vda", "default", "")])
         shown = doc.xpath("//button[contains(concat(' ', @class, ' '), ' disabled ')]")
         self.assertGreater(len(shown), 5)
         self.assertEqual([b for b in shown if b.get("disabled") is None], [])
-        for action in ("resizevm_cpu", "change_options", "set_video_model", "change_xml", "detach_vol", "delete_vol"):
+        for action in ("resizevm_cpu", "change_options", "set_video_model", "detach_vol", "delete_vol"):
             with self.subTest(action):
                 (form,) = doc.xpath("//form[@action=$a]", a=reverse(f"instances:{action}", args=[self.instance.id]))
                 self.assertTrue(all(b.get("disabled") is not None for b in form.xpath(".//button")))
 
-    def test_the_xml_editor_reviews_a_change_only_while_the_vm_is_off(self):
-        # static/js/xml_editor.js opens the review dialog on Change
-        doc = self.page(status=5)
-        self.assertEqual(len(doc.xpath("//form[@id='xml-form']//button[@type='submit']")), 1)
-        self.assertEqual(len(doc.xpath("//div[@id='xml-review']//button[@id='xml-review-save']")), 1)
-        self.assertEqual(self.page().xpath("//div[@id='xml-review']"), [])
+    def test_the_xml_editor_shows_the_definition_for_the_next_start(self):
+        # static/js/xml_editor.js opens the review dialog on Change, also while the VM runs
+        for status in (5, 1):
+            with self.subTest(status=status):
+                doc = self.page(status=status)
+                (button,) = doc.xpath("//form[@id='xml-form']//button[@type='submit']")
+                self.assertIsNone(button.get("disabled"))
+                self.assertEqual(len(doc.xpath("//div[@id='xml-review']//button[@id='xml-review-save']")), 1)
+                self.assertEqual(bool(doc.xpath("//p[@id='xml-next-start']")), status != 5)
 
     def test_the_boot_video_and_console_forms_show_the_pending_definition(self):
         cd = {"dev": "sda", "image": "pending.iso", "storage": "default", "path": "/pool/pending.iso", "bus": "sata"}
diff --git a/instances/views.py b/instances/views.py
index db433c0f..f27008d3 100755
--- a/instances/views.py
+++ b/instances/views.py
@@ -1457,17 +1457,14 @@ def set_bootorder(request, pk):
 def change_xml(request, pk):
     """
     The XML editor's dialog: without confirm, the lines the edited XML changes
-    in the definition, to review; with confirm, the edited XML is defined.
+    in the persistent definition, to review; with confirm, the edited XML is
+    defined. A running VM uses it at its next start.
     Only over the definition the editor was opened with (base), so a change
     made since is not overwritten; a form posts its line breaks as CRLF. A refusal comes back to the dialog and the
     edited XML stays in the editor.
     """
     instance = get_instance(request.user, pk)
     new_xml = request.POST.get("inst_xml", "")
-    # The editor is filled while the VM is shut off; once it runs, the posted
-    # XML would overwrite changes made since.
-    if instance.proxy.get_status() != 5:
-        return JsonResponse({"error": _("Power off the instance to change its XML")}, status=409)
     if not new_xml.strip():
         return JsonResponse({"error": _("The XML is empty")}, status=400)
     current = instance.inst_xml
@@ -1482,7 +1479,10 @@ def change_xml(request, pk):
             instance.proxy._defineXML(new_xml)
     except libvirtError as err:
         return JsonResponse({"error": error_text(request, err)}, status=400)
-    messages.success(request, _("The XML definition was saved."))
+    if instance.proxy.get_status() == 5:
+        messages.success(request, _("The XML definition was saved."))
+    else:
+        messages.success(request, _("The XML definition was saved; the VM uses it from its next start."))
     return JsonResponse({"saved": True})
 
 
diff --git a/static/js/xml_editor.js b/static/js/xml_editor.js
index ffda4cb6..fa7b6aa7 100644
--- a/static/js/xml_editor.js
+++ b/static/js/xml_editor.js
@@ -10,9 +10,6 @@
     editor.getSession().setMode("ace/mode/xml");
     var base = editor.getValue(); // the definition the editor opened with
     var dialog = document.getElementById("xml-review");
-    if (!dialog) {
-        return; // a running VM's editor only shows its XML
-    }
     var modal = bootstrap.Modal.getOrCreateInstance(dialog);
     var error = document.getElementById("xml-review-error");
     var same = document.getElementById("xml-review-same");