diff --git a/django_mongodb_backend/functions.py b/django_mongodb_backend/functions.py
index c5d3a270e..9339840cc 100644
--- a/django_mongodb_backend/functions.py
+++ b/django_mongodb_backend/functions.py
@@ -109,7 +109,7 @@ def extract(self, compiler, connection):
 def func(self, compiler, connection):
     lhs_mql = process_lhs(self, compiler, connection, as_expr=True)
     if self.function is None:
-        raise NotSupportedError(f"{self} may need an as_mql() method.")
+        raise NotSupportedError(f"{self.__class__.__name__} may need an as_mql() method.")
     operator = MONGO_OPERATORS.get(self.__class__, self.function.lower())
     return {f"${operator}": lhs_mql}
 
diff --git a/tests/db_functions_/tests.py b/tests/db_functions_/tests.py
index 23029d42e..03aad92cd 100644
--- a/tests/db_functions_/tests.py
+++ b/tests/db_functions_/tests.py
@@ -5,6 +5,6 @@
 
 class FuncTests(SimpleTestCase):
     def test_no_as_mql(self):
-        msg = "Func() may need an as_mql() method."
+        msg = "Func may need an as_mql() method."
         with self.assertRaisesMessage(NotSupportedError, msg):
             Func().as_mql(None, None)