diff --git a/src/dowc/accounts/tests/factories.py b/src/dowc/accounts/tests/factories.py
index c6f5848..751c8e8 100644
--- a/src/dowc/accounts/tests/factories.py
+++ b/src/dowc/accounts/tests/factories.py
@@ -3,7 +3,7 @@
 
 class UserFactory(factory.django.DjangoModelFactory):
     username = factory.Sequence(lambda n: f"user-{n}")
-    email = factory.Sequence(lambda n: f"user-{n}@kownsl.nl")
+    email = factory.Sequence(lambda n: f"user-{n}@dowc.nl")
     password = factory.PostGenerationMethodCall("set_password", "secret")
 
     class Meta:
diff --git a/src/dowc/api/serializers.py b/src/dowc/api/serializers.py
index a4a487a..86309fd 100644
--- a/src/dowc/api/serializers.py
+++ b/src/dowc/api/serializers.py
@@ -202,10 +202,15 @@ class DocumentStatusSerializer(serializers.ModelSerializer):
         help_text=_("URL-reference to document in DRC API."),
         source="unversioned_url",
     )
+    locked_by = serializers.EmailField(
+        read_only=True,
+        source="user.email",
+        help_text=_("Email address of user that created DocumentFile."),
+    )
 
     class Meta:
         model = DocumentFile
-        fields = ("document", "uuid")
+        fields = ("document", "uuid", "locked_by")
         extra_kwargs = {
             "uuid": {
                 "read_only": True,
diff --git a/src/dowc/api/tests/test_documentfile_api.py b/src/dowc/api/tests/test_documentfile_api.py
index 0912fe6..35e3781 100644
--- a/src/dowc/api/tests/test_documentfile_api.py
+++ b/src/dowc/api/tests/test_documentfile_api.py
@@ -473,10 +473,12 @@ def test_retrieve_documentfiles_on_url(self, m):
         df1 = DocumentFileFactory.create(
             unversioned_url="http://some-unversioned-url.com/1",
             purpose=DocFileTypes.write,
+            user=self.user,
         )
         df2 = DocumentFileFactory.create(
             unversioned_url="http://some-unversioned-url.com/2",
             purpose=DocFileTypes.write,
+            user=self.user,
         )
 
         # Retrieve documentfiles with this data
@@ -502,10 +504,12 @@ def test_retrieve_documentfiles_on_url(self, m):
                 {
                     "document": "http://some-unversioned-url.com/1",
                     "uuid": str(df1.uuid),
+                    "lockedBy": self.user.email,
                 },
                 {
                     "document": "http://some-unversioned-url.com/2",
                     "uuid": str(df2.uuid),
+                    "lockedBy": self.user.email,
                 },
             ],
         )
@@ -523,6 +527,7 @@ def test_retrieve_documentfiles_on_zaak(self, m):
             unversioned_url="http://some-unversioned-url.com/2",
             purpose=DocFileTypes.write,
             zaak="http://some-other-zaak.nl/",
+            user=self.user,
         )
 
         # Retrieve documentfiles with this data
@@ -543,6 +548,7 @@ def test_retrieve_documentfiles_on_zaak(self, m):
                 {
                     "document": "http://some-unversioned-url.com/2",
                     "uuid": str(df2.uuid),
+                    "lockedBy": self.user.email,
                 },
             ],
         )