diff --git a/django/core/management/sql.py b/django/core/management/sql.py
index 4832f27b07..841f55de0e 100644
--- a/django/core/management/sql.py
+++ b/django/core/management/sql.py
@@ -202,7 +202,7 @@ def custom_sql_for_model(model, style, connection):
         sql_files.append(os.path.join(app_dir, "%s.sql" % opts.model_name))
     for sql_file in sql_files:
         if os.path.exists(sql_file):
-            with codecs.open(sql_file, 'r' if six.PY3 else 'U', encoding=settings.FILE_CHARSET) as fp:
+            with codecs.open(sql_file, 'r', encoding=settings.FILE_CHARSET) as fp:
                 output.extend(connection.ops.prepare_sql_script(fp.read(), _allow_fallback=True))
     return output