diff --git a/sphinx/pycode/ast.py b/sphinx/pycode/ast.py
index 0b403b61e..3d2af3426 100644
--- a/sphinx/pycode/ast.py
+++ b/sphinx/pycode/ast.py
@@ -189,7 +189,7 @@ class _UnparseVisitor(ast.NodeVisitor):
             return "()"
 
     if sys.version_info >= (3, 6):
-        def visit_Constant(self, node: ast.Constant) -> str:
+        def visit_Constant(self, node: ast.Constant) -> str:  # type: ignore
             if node.value is Ellipsis:
                 return "..."
             else:
diff --git a/sphinx/util/__init__.py b/sphinx/util/__init__.py
index f3659cc4c..f0794bed0 100644
--- a/sphinx/util/__init__.py
+++ b/sphinx/util/__init__.py
@@ -16,8 +16,8 @@ import re
 import sys
 import tempfile
 import traceback
-import warnings
 import unicodedata
+import warnings
 from datetime import datetime
 from importlib import import_module
 from os import path