diff --git a/src/librustc_borrowck/lib.rs b/src/librustc_borrowck/lib.rs
index 65e9b79224181..1aa27f8b32b17 100644
--- a/src/librustc_borrowck/lib.rs
+++ b/src/librustc_borrowck/lib.rs
@@ -25,6 +25,7 @@
 #![feature(staged_api)]
 #![feature(associated_consts)]
 #![feature(nonzero)]
+#![feature(question_mark)]
 #[macro_use] extern crate log;
 #[macro_use] extern crate syntax;