diff --git a/CHANGELOG.txt b/CHANGELOG.txt
index 68a21731b8..ce6d2566f8 100644
--- a/CHANGELOG.txt
+++ b/CHANGELOG.txt
@@ -1,8 +1,15 @@
 Changelog
 =========
 
+0.4 (xx.xx.20xx)
+~~~~~~~~~~~~~~~~~~
  * When logged in user visits login page, they are now redirected to the dashboard
- * Fix: Deleting an item from an InlinePanel, then generating a validation error on saving, no longer causes the deleted item to confusingly reappear with an error of it's own.
+
+0.3.1 (xx.xx.20xx)
+~~~~~~~~~~~~~~~~~~
+ * Fix: When constructing dummy requests for pages with no routable URL, fall back on a hostname from ALLOWED_HOSTS and finally 'localhost', to avoid 'Invalid HTTP_HOST header' errors on preview when DEBUG=False.
+ * Fix: Ensure that url_path is populated when previewing a newly created page, to avoid unnecessarily taking the above fallback.
+ * Fix: Deleting an item from an InlinePanel, then generating a validation error on saving, no longer causes the deleted item to confusingly reappear with an error of its own.
 
 0.3 (28.05.2014)
 ~~~~~~~~~~~~~~~~
diff --git a/wagtail/wagtailadmin/views/pages.py b/wagtail/wagtailadmin/views/pages.py
index 809497d83e..9bf6dbf444 100644
--- a/wagtail/wagtailadmin/views/pages.py
+++ b/wagtail/wagtailadmin/views/pages.py
@@ -349,6 +349,10 @@ def preview_on_create(request, content_type_app_name, content_type_model_name, p
     if form.is_valid():
         form.save(commit=False)
 
+        # ensure that our unsaved page instance has a suitable url set
+        parent_page = get_object_or_404(Page, id=parent_page_id).specific
+        page.set_url_path(parent_page)
+
         # This view will generally be invoked as an AJAX request; as such, in the case of
         # an error Django will return a plaintext response. This isn't what we want, since
         # we will be writing the response back to an HTML page regardless of success or
diff --git a/wagtail/wagtailcore/models.py b/wagtail/wagtailcore/models.py
index f72e6f6f9e..30ffc8a77f 100644
--- a/wagtail/wagtailcore/models.py
+++ b/wagtail/wagtailcore/models.py
@@ -581,7 +581,12 @@ class Page(MP_Node, ClusterableModel, Indexed):
             path = url_info.path
             port = url_info.port or 80
         else:
-            hostname = 'example.com'
+            # Cannot determine a URL to this page - cobble one together based on
+            # whatever we find in ALLOWED_HOSTS
+            try:
+                hostname = settings.ALLOWED_HOSTS[0]
+            except IndexError:
+                hostname = 'localhost'
             path = '/'
             port = 80