diff --git a/glowtables/table.py b/glowtables/table.py
index cb0a484..905386d 100644
--- a/glowtables/table.py
+++ b/glowtables/table.py
@@ -86,7 +86,7 @@ class LiteralField(Field[rdflib.Literal]):
         if value is None:
             if self.default is None:
                 raise ValueError(f"{self.id} value is unexpectedly None")
-            return sort_key(self.default)
+            return self.sort_key(self.default)
         return value
 
     def sparql(
diff --git a/glowtables/tests/table_test.py b/glowtables/tests/table_test.py
index b8af124..f43d00e 100644
--- a/glowtables/tests/table_test.py
+++ b/glowtables/tests/table_test.py
@@ -75,7 +75,7 @@ def test_default_value() -> None:
         "display_name",
         {Language("en"): "Name"},
         rdflib.URIRef("http://example.org/display-name"),
-        default=rdflib.Literal("Anonymous CPU")
+        default=rdflib.Literal("Anonymous CPU"),
     )
     table = Table(
         fields=[name_field],
@@ -122,4 +122,3 @@ def test_field_id_clash() -> None:
             fields=[name_field, display_name_field],
             constraints="",
         )
-