diff --git a/sphinx/locale/__init__.py b/sphinx/locale/__init__.py
index 2ee353d76..bd7e4899b 100644
--- a/sphinx/locale/__init__.py
+++ b/sphinx/locale/__init__.py
@@ -57,7 +57,7 @@ class _TranslationProxy(UserString):
         self._args = args
 
     @property
-    def data(self):
+    def data(self):  # type: ignore
         # type: () -> unicode
         return self._func(*self._args)