diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -3959,6 +3959,7 @@
         __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
         __set_long_cap(0);
         __set_short_size(0);
+        traits_type::assign(*__get_short_pointer(), value_type());
     }
 }