diff --git a/bookwyrm/models/fields.py b/bookwyrm/models/fields.py
index 1a8c082a..0e2a42e5 100644
--- a/bookwyrm/models/fields.py
+++ b/bookwyrm/models/fields.py
@@ -427,7 +427,7 @@ class ImageField(ActivitypubFieldMixin, models.ImageField):
         """returns an absolute URL for the image"""
         name = getattr(value, self.name)
         if name is None:
-            return
+            return None
 
         url = filepath_to_uri(name)
         if url is not None:
diff --git a/bookwyrm/tests/models/test_status_model.py b/bookwyrm/tests/models/test_status_model.py
index 355caab9..a01d8679 100644
--- a/bookwyrm/tests/models/test_status_model.py
+++ b/bookwyrm/tests/models/test_status_model.py
@@ -177,7 +177,7 @@ class Status(TestCase):
         self.assertEqual(activity["attachment"][0].type, "Document")
         self.assertEqual(
             activity["attachment"][0].url,
-            "https://%s%s" % (settings.DOMAIN, self.book.cover.url),
+            "https://%s%s" % (settings.MEDIA_FULL_URL, self.book.cover.url),
         )
         self.assertEqual(activity["attachment"][0].name, "Test Edition")
 
@@ -208,7 +208,7 @@ class Status(TestCase):
         self.assertEqual(activity["attachment"][0].type, "Document")
         self.assertEqual(
             activity["attachment"][0].url,
-            "https://%s%s" % (settings.DOMAIN, self.book.cover.url),
+            "https://%s%s" % (settings.MEDIA_FULL_URL, self.book.cover.url),
         )
         self.assertEqual(activity["attachment"][0].name, "Test Edition")
 
@@ -246,7 +246,7 @@ class Status(TestCase):
         self.assertEqual(activity["attachment"][0].type, "Document")
         self.assertEqual(
             activity["attachment"][0].url,
-            "https://%s%s" % (settings.DOMAIN, self.book.cover.url),
+            "https://%s%s" % (settings.MEDIA_FULL_URL, self.book.cover.url),
         )
         self.assertEqual(activity["attachment"][0].name, "Test Edition")
 
@@ -287,7 +287,7 @@ class Status(TestCase):
         self.assertEqual(activity["attachment"][0].type, "Document")
         self.assertEqual(
             activity["attachment"][0].url,
-            "https://%s%s" % (settings.DOMAIN, self.book.cover.url),
+            "https://%s%s" % (settings.MEDIA_FULL_URL, self.book.cover.url),
         )
         self.assertEqual(activity["attachment"][0].name, "Test Edition")
 
@@ -309,7 +309,7 @@ class Status(TestCase):
         self.assertEqual(activity["attachment"][0].type, "Document")
         self.assertEqual(
             activity["attachment"][0].url,
-            "https://%s%s" % (settings.DOMAIN, self.book.cover.url),
+            "https://%s%s" % (settings.MEDIA_FULL_URL, self.book.cover.url),
         )
         self.assertEqual(activity["attachment"][0].name, "Test Edition")
 
@@ -331,7 +331,7 @@ class Status(TestCase):
         self.assertEqual(activity["attachment"][0].type, "Document")
         self.assertEqual(
             activity["attachment"][0].url,
-            "https://%s%s" % (settings.DOMAIN, self.book.cover.url),
+            "https://%s%s" % (settings.MEDIA_FULL_URL, self.book.cover.url),
         )
         self.assertEqual(activity["attachment"][0].name, "Test Edition")