diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs
index 437b0257a975..f3d76a8f12f1 100644
--- a/src/librustc_driver/driver.rs
+++ b/src/librustc_driver/driver.rs
@@ -682,7 +682,7 @@ pub fn collect_crate_types(session: &Session,
         if base.len() == 0 {
             base.push(link::default_output_for_target(session));
         }
-        base.as_mut_slice().sort();
+        base.sort();
         base.dedup();
     }