diff --git a/src/documents/filters.py b/src/documents/filters.py
index b3c92eba3..4614d292b 100755
--- a/src/documents/filters.py
+++ b/src/documents/filters.py
@@ -98,12 +98,14 @@ class DocumentFilterSet(FilterSet):
             "added": DATE_KWARGS,
             "modified": DATE_KWARGS,
 
+            "correspondent": ["isnull"],
             "correspondent__id": ID_KWARGS,
             "correspondent__name": CHAR_KWARGS,
 
             "tags__id": ID_KWARGS,
             "tags__name": CHAR_KWARGS,
 
+            "document_type": ["isnull"],
             "document_type__id": ID_KWARGS,
             "document_type__name": CHAR_KWARGS,