diff --git a/src/wagtail_headless_preview/models.py b/src/wagtail_headless_preview/models.py
index 415c1b4..f2316a6 100644
--- a/src/wagtail_headless_preview/models.py
+++ b/src/wagtail_headless_preview/models.py
@@ -1,16 +1,24 @@
 import datetime
 import json
 
+from typing import TYPE_CHECKING, Optional
+
 from django.contrib.contenttypes.models import ContentType
 from django.core.signing import TimestampSigner
 from django.db import models
 from django.shortcuts import redirect, render
 from django.utils.http import urlencode
+from wagtail.models import Site
 
 from wagtail_headless_preview.settings import headless_preview_settings
 from wagtail_headless_preview.signals import preview_update
 
 
+if TYPE_CHECKING:
+    from django.http import HttpRequest
+    from wagtail.models import Page, Site
+
+
 class PagePreview(models.Model):
     token = models.CharField(max_length=255, unique=True)
     content_type = models.ForeignKey(
@@ -19,7 +27,7 @@ class PagePreview(models.Model):
     content_json = models.TextField()
     created_at = models.DateField(auto_now_add=True)
 
-    def as_page(self):
+    def as_page(self) -> "Page":
         content = json.loads(self.content_json)
         page_model = ContentType.objects.get_for_id(
             content["content_type"]
@@ -34,7 +42,7 @@ def garbage_collect(cls):
         cls.objects.filter(created_at__lt=yesterday).delete()
 
 
-def get_client_root_url_from_site(site):
+def get_client_root_url_from_site(site) -> str:
     try:
         root_url = headless_preview_settings.CLIENT_URLS[site.hostname]
     except (AttributeError, KeyError):
@@ -48,17 +56,35 @@ def get_client_root_url_from_site(site):
     return root_url
 
 
-class HeadlessPreviewMixin:
+class HeadlessBase:
+    def _get_site_from_request(self, request: "HttpRequest") -> "Site":
+        """
+        Copy of Page.get_site() which passes the request object to Page.get_url_parts()
+        """
+        url_parts = self.get_url_parts(request=request)
+        if url_parts is None:
+            # page is not routable
+            return
+
+        site_id, root_url, page_path = url_parts
+
+        return Site.objects.get(id=site_id)
+
+    def get_client_root_url(self, request: "HttpRequest") -> str:
+        return get_client_root_url_from_site(self._get_site_from_request(request))
+
+
+class HeadlessPreviewMixin(HeadlessBase):
     @classmethod
-    def get_preview_signer(cls):
+    def get_preview_signer(cls) -> TimestampSigner:
         return TimestampSigner(salt="headlesspreview.token")
 
     @classmethod
-    def get_content_type_str(cls):
+    def get_content_type_str(cls) -> str:
         return cls._meta.app_label + "." + cls.__name__.lower()
 
     @classmethod
-    def get_page_from_preview_token(cls, token):
+    def get_page_from_preview_token(cls, token: str) -> Optional["Page"]:
         content_type = ContentType.objects.get_for_model(cls)
 
         # Check token is valid
@@ -71,7 +97,16 @@ def get_page_from_preview_token(cls, token):
         except PagePreview.DoesNotExist:
             return
 
-    def create_page_preview(self):
+    def update_page_preview(self, token: str) -> PagePreview:
+        return PagePreview.objects.update_or_create(
+            token=token,
+            defaults={
+                "content_type": self.content_type,
+                "content_json": self.to_json(),
+            },
+        )
+
+    def create_page_preview(self) -> PagePreview:
         if self.pk is None:
             identifier = (
                 f"parent_id={self.get_parent().pk};page_type={self._meta.label}"
@@ -86,26 +121,14 @@ def create_page_preview(self):
 
         return preview
 
-    def update_page_preview(self, token):
-        return PagePreview.objects.update_or_create(
-            token=token,
-            defaults={
-                "content_type": self.content_type,
-                "content_json": self.to_json(),
-            },
-        )
-
-    def get_client_root_url(self):
-        return get_client_root_url_from_site(self.get_site())
-
-    def get_preview_url(self, token):
+    def get_preview_url(self, request: "HttpRequest", token: str) -> str:
         return (
-            self.get_client_root_url()
+            self.get_client_root_url(request)
             + "?"
             + urlencode({"content_type": self.get_content_type_str(), "token": token})
         )
 
-    def serve_preview(self, request, preview_mode):
+    def serve_preview(self, request: "HttpRequest", preview_mode):
         PagePreview.garbage_collect()
         page_preview = self.create_page_preview()
         page_preview.save()
@@ -113,7 +136,7 @@ def serve_preview(self, request, preview_mode):
         # Send the preview_update signal. Other apps can implement their own handling
         preview_update.send(sender=HeadlessPreviewMixin, token=page_preview.token)
 
-        preview_url = self.get_preview_url(page_preview.token)
+        preview_url = self.get_preview_url(request, page_preview.token)
         if headless_preview_settings.REDIRECT_ON_PREVIEW:
             return redirect(preview_url)
 
@@ -126,8 +149,8 @@ def serve_preview(self, request, preview_mode):
         return response
 
 
-class HeadlessServeMixin:
-    def serve(self, request):
+class HeadlessServeMixin(HeadlessBase):
+    def serve(self, request: "HttpRequest"):
         """
         Mixin overriding the default serve method with a redirect.
         The URL of the requested page is kept the same, only the host is
@@ -136,10 +159,12 @@ def serve(self, request):
         However, you can enforce a single host using the HEADLESS_SERVE_BASE_URL
         setting.
         """
+
         if headless_preview_settings.SERVE_BASE_URL:
             base_url = headless_preview_settings.SERVE_BASE_URL
         else:
-            base_url = get_client_root_url_from_site(self.get_site())
+            base_url = self.get_client_root_url(request)
+
         site_id, site_root, relative_page_url = self.get_url_parts(request)
         return redirect(f"{base_url.rstrip('/')}{relative_page_url}")