diff --git a/aleksis/apps/alsijil/schema/documentation.py b/aleksis/apps/alsijil/schema/documentation.py
index 68e327529272ce6c28ad765c9a3d8a5b0fdbfe37..4e8f51ba518d55474a0b65f819a0010a0cf8db12 100644
--- a/aleksis/apps/alsijil/schema/documentation.py
+++ b/aleksis/apps/alsijil/schema/documentation.py
@@ -165,9 +165,13 @@ class DocumentationBatchCreateOrUpdateMutation(graphene.Mutation):
             if not info.context.user.has_perm("alsijil.edit_documentation_rule", obj):
                 raise PermissionDenied()
 
-            obj.topic = doc.topic or ""
-            obj.homework = doc.homework or ""
-            obj.group_note = doc.group_note or ""
+            if doc.topic:
+                obj.topic = doc.topic
+            if doc.homework:
+                obj.homework = doc.homework
+            if doc.group_note:
+                obj.group_note = doc.group_note
+
             obj.save()
             return obj