diff --git a/src/lib.rs b/src/lib.rs
index d11b916..ca95880 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,7 +3,7 @@
 //! the [std documentation](https://doc.rust-lang.org/nightly/std/io/index.html)
 //! for a full description of the functionality.
 #![allow(stable_features,unused_features,incomplete_features)]
-#![feature(question_mark,const_fn,copy_from_slice,try_from,str_internals,align_offset,
+#![feature(question_mark,copy_from_slice,try_from,str_internals,align_offset,
        doc_spotlight,slice_internals,maybe_uninit_ref,mem_take,specialization)]
 #![cfg_attr(any(feature="alloc",feature="collections"),feature(alloc,allocator_api))]
 #![cfg_attr(feature="collections",feature(vec_spare_capacity,maybe_uninit_slice,