diff --git a/libcxx/include/__vector/vector_bool.h b/libcxx/include/__vector/vector_bool.h
index 525fc35b26cc9..8658745b8a8f9 100644
--- a/libcxx/include/__vector/vector_bool.h
+++ b/libcxx/include/__vector/vector_bool.h
@@ -442,7 +442,6 @@ class _LIBCPP_TEMPLATE_VIS vector<bool, _Allocator> {
   template <class _InputIterator, class _Sentinel>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
   __construct_at_end(_InputIterator __first, _Sentinel __last, size_type __n);
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __append(size_type __n, const_reference __x);
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reference __make_ref(size_type __pos) _NOEXCEPT {
     return reference(__begin_ + __pos / __bits_per_word, __storage_type(1) << __pos % __bits_per_word);
   }