diff --git a/mssql/base.py b/mssql/base.py
index 4d83a2e..c69046a 100644
--- a/mssql/base.py
+++ b/mssql/base.py
@@ -597,6 +597,8 @@ def _as_sql_type(self, typ, value):
             return 'TIME'
         elif isinstance(value, UUID):
             return 'uniqueidentifier'
+        elif isinstance(value, bytes):
+            return 'VARBINARY'
         else:
             raise NotImplementedError('Not supported type %s (%s)' % (type(value), repr(value)))
 
diff --git a/testapp/tests/test_queries.py b/testapp/tests/test_queries.py
index 785db02..5426723 100644
--- a/testapp/tests/test_queries.py
+++ b/testapp/tests/test_queries.py
@@ -1,8 +1,8 @@
 import django.db.utils
-from django.db import connections
-from django.test import TransactionTestCase
+from django.db import connections, connection
+from django.test import TransactionTestCase, TestCase
 
-from ..models import Author
+from ..models import Author, BinaryData
 
 class TestTableWithTrigger(TransactionTestCase):
     def test_insert_into_table_with_trigger(self):
@@ -27,4 +27,9 @@ def test_insert_into_table_with_trigger(self):
         finally:
             with connection.schema_editor() as cursor:
                 cursor.execute("DROP TRIGGER TestTrigger")
-            connection.features_class.can_return_rows_from_bulk_insert = old_return_rows_flag
\ No newline at end of file
+            connection.features_class.can_return_rows_from_bulk_insert = old_return_rows_flag
+
+class TestBinaryfieldGroupby(TestCase):
+    def test_varbinary(self):
+        with connection.cursor() as cursor:
+            cursor.execute(f"SELECT binary FROM {BinaryData._meta.db_table} WHERE binary = %s GROUP BY binary", [bytes("ABC", 'utf-8')])