diff --git a/src/lib.rs b/src/lib.rs
index d32b52c..e0d8131 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,9 +1,7 @@
 #![crate_name = "bytes"]
 #![unstable]
 
-#![feature(core)]
-#![feature(alloc)]
-#![feature(unsafe_no_drop_flag)]
+#![feature(alloc, core, io, unsafe_no_drop_flag)]
 
 pub use byte_buf::{ByteBuf, ROByteBuf, MutByteBuf};
 pub use byte_str::{SeqByteStr, SmallByteStr, SmallByteStrBuf};