diff --git a/server/szurubooru/api/tag_category_api.py b/server/szurubooru/api/tag_category_api.py
index ccbe4e89..0b9eb660 100644
--- a/server/szurubooru/api/tag_category_api.py
+++ b/server/szurubooru/api/tag_category_api.py
@@ -57,11 +57,14 @@ class TagCategoryDetailApi(BaseApi):
         if not category:
             raise tag_categories.TagCategoryNotFoundError(
                 'Tag category %r not found.' % category_name)
+        auth.verify_privilege(ctx.user, 'tag_categories:delete')
+        if len(tag_categories.get_all_category_names()) == 1:
+            raise tag_categories.TagCategoryIsInUseError(
+                'Cannot delete the default category.')
         if category.tag_count > 0:
             raise tag_categories.TagCategoryIsInUseError(
                 'Tag category has some usages and cannot be deleted. ' +
                 'Please remove this category from relevant tags first..')
-        auth.verify_privilege(ctx.user, 'tag_categories:delete')
         ctx.session.delete(category)
         ctx.session.commit()
         tags.export_to_json()
diff --git a/server/szurubooru/tests/api/test_tag_category_deleting.py b/server/szurubooru/tests/api/test_tag_category_deleting.py
index c298a557..7d7422ed 100644
--- a/server/szurubooru/tests/api/test_tag_category_deleting.py
+++ b/server/szurubooru/tests/api/test_tag_category_deleting.py
@@ -54,6 +54,15 @@ def test_trying_to_delete_used(test_ctx, tag_factory):
             'category')
     assert db.session().query(db.TagCategory).count() == 1
 
+def test_trying_to_delete_last(test_ctx, tag_factory):
+    db.session().add(test_ctx.tag_category_factory(name='root'))
+    db.session().commit()
+    with pytest.raises(tag_categories.TagCategoryIsInUseError):
+        result = test_ctx.api.delete(
+            test_ctx.context_factory(
+                user=test_ctx.user_factory(rank='regular_user')),
+            'root')
+
 def test_trying_to_delete_non_existing(test_ctx):
     with pytest.raises(tag_categories.TagCategoryNotFoundError):
         test_ctx.api.delete(