diff --git a/server/szurubooru/search/configs/post_search_config.py b/server/szurubooru/search/configs/post_search_config.py
index 3a578478..743f5b64 100644
--- a/server/szurubooru/search/configs/post_search_config.py
+++ b/server/szurubooru/search/configs/post_search_config.py
@@ -62,6 +62,22 @@ def _create_score_filter(score):
     return wrapper
 
 
+def _create_user_filter():
+    def wrapper(query, criterion, negated):
+        if isinstance(criterion, criteria.PlainCriterion) \
+                and not criterion.value:
+            expr = db.Post.user_id == None  # sic
+            if negated:
+                expr = ~expr
+            return query.filter(expr)
+        return search_util.create_subquery_filter(
+            db.Post.user_id,
+            db.User.user_id,
+            db.User.name,
+            search_util.create_str_filter)(query, criterion, negated)
+    return wrapper
+
+
 class PostSearchConfig(BaseSearchConfig):
     def on_search_query_parsed(self, search_query):
         new_special_tokens = []
@@ -138,11 +154,7 @@ class PostSearchConfig(BaseSearchConfig):
                 lambda subquery: subquery.join(db.Tag).join(db.TagName)),
             'score': search_util.create_num_filter(db.Post.score),
             ('uploader', 'upload', 'submit'):
-                search_util.create_subquery_filter(
-                    db.Post.user_id,
-                    db.User.user_id,
-                    db.User.name,
-                    search_util.create_str_filter),
+                _create_user_filter(),
             'comment': search_util.create_subquery_filter(
                 db.Post.post_id,
                 db.Comment.post_id,
diff --git a/server/szurubooru/tests/search/configs/test_post_search_config.py b/server/szurubooru/tests/search/configs/test_post_search_config.py
index 0c87f993..c4bed6d0 100644
--- a/server/szurubooru/tests/search/configs/test_post_search_config.py
+++ b/server/szurubooru/tests/search/configs/test_post_search_config.py
@@ -131,12 +131,15 @@ def test_filter_by_score(
 
 
 @pytest.mark.parametrize('input,expected_post_ids', [
+    ('uploader:', [4]),
     ('uploader:u1', [1]),
     ('uploader:u3', [3]),
     ('uploader:u1,u3', [1, 3]),
+    ('upload:', [4]),
     ('upload:u1', [1]),
     ('upload:u3', [3]),
     ('upload:u1,u3', [1, 3]),
+    ('submit:', [4]),
     ('submit:u1', [1]),
     ('submit:u3', [3]),
     ('submit:u1,u3', [1, 3]),
@@ -146,10 +149,11 @@ def test_filter_by_uploader(
     post1 = post_factory(id=1)
     post2 = post_factory(id=2)
     post3 = post_factory(id=3)
+    post4 = post_factory(id=4)
     post1.user = user_factory(name='u1')
     post2.user = user_factory(name='u2')
     post3.user = user_factory(name='u3')
-    db.session.add_all([post1, post2, post3])
+    db.session.add_all([post1, post2, post3, post4])
     verify_unpaged(input, expected_post_ids)