diff --git a/contrib/libc++/include/__functional_03 b/contrib/libc++/include/__functional_03
index f9a3d9766255..2582601738e4 100644
--- a/contrib/libc++/include/__functional_03
+++ b/contrib/libc++/include/__functional_03
@@ -33,28 +33,28 @@ public:
     // invoke
 
     typename __invoke_return<type>::type
-       operator() ()
+       operator() () const
        {
            return __invoke(__f_);
        }
 
     template <class _A0>
        typename __invoke_return0<type, _A0>::type
-          operator() (_A0& __a0)
+          operator() (_A0& __a0) const
           {
               return __invoke(__f_, __a0);
           }
 
     template <class _A0, class _A1>
        typename __invoke_return1<type, _A0, _A1>::type
-          operator() (_A0& __a0, _A1& __a1)
+          operator() (_A0& __a0, _A1& __a1) const
           {
               return __invoke(__f_, __a0, __a1);
           }
 
     template <class _A0, class _A1, class _A2>
        typename __invoke_return2<type, _A0, _A1, _A2>::type
-          operator() (_A0& __a0, _A1& __a1, _A2& __a2)
+          operator() (_A0& __a0, _A1& __a1, _A2& __a2) const
           {
               return __invoke(__f_, __a0, __a1, __a2);
           }
diff --git a/contrib/libc++/include/functional b/contrib/libc++/include/functional
index d40f70af40ba..891ed460ac6b 100644
--- a/contrib/libc++/include/functional
+++ b/contrib/libc++/include/functional
@@ -1221,7 +1221,7 @@ public:
     template <class... _ArgTypes>
        _LIBCPP_INLINE_VISIBILITY
        typename __invoke_return<type, _ArgTypes...>::type
-          operator() (_ArgTypes&&... __args)
+          operator() (_ArgTypes&&... __args) const
           {
               return __invoke(__f_, _VSTD::forward<_ArgTypes>(__args)...);
           }