diff --git a/src/libcollections/str.rs b/src/libcollections/str.rs
index 4bd86bb60695..f2d8efdfde5a 100644
--- a/src/libcollections/str.rs
+++ b/src/libcollections/str.rs
@@ -780,7 +780,7 @@ impl str {
     ///
     /// # Examples
     /// ```
-    /// # #![feature(collections)]
+    /// # #![feature(str_split_at)]
     /// let s = "Löwe 老虎 Léopard";
     /// let first_space = s.find(' ').unwrap_or(s.len());
     /// let (a, b) = s.split_at(first_space);
diff --git a/src/libcollectionstest/lib.rs b/src/libcollectionstest/lib.rs
index 233623b8a5e4..d161dc7a287f 100644
--- a/src/libcollectionstest/lib.rs
+++ b/src/libcollectionstest/lib.rs
@@ -44,6 +44,7 @@
 #![feature(str_char)]
 #![feature(str_escape)]
 #![feature(str_match_indices)]
+#![feature(str_split_at)]
 #![feature(str_utf16)]
 #![feature(box_str)]
 #![feature(subslice_offset)]
diff --git a/src/test/compile-fail/str-mut-idx-2.rs b/src/test/compile-fail/str-mut-idx-2.rs
deleted file mode 100644
index aa05d7d5c54d..000000000000
--- a/src/test/compile-fail/str-mut-idx-2.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-fn mutate(mut s: &mut str) {
-    let _s: &mut str = &mut s[1..2];
-    //~^ ERROR cannot borrow immutable indexed content as mutable
-}
-
-pub fn main() {}
diff --git a/src/test/compile-fail/str-mut-idx.rs b/src/test/compile-fail/str-mut-idx.rs
index 88e90c8244d8..73abe6cb59db 100644
--- a/src/test/compile-fail/str-mut-idx.rs
+++ b/src/test/compile-fail/str-mut-idx.rs
@@ -13,10 +13,11 @@ fn bot<T>() -> T { loop {} }
 fn mutate(s: &mut str) {
     s[1..2] = bot();
     //~^ ERROR `core::marker::Sized` is not implemented for the type `str`
-    //~^^ ERROR `core::marker::Sized` is not implemented for the type `str`
+    //~| ERROR `core::marker::Sized` is not implemented for the type `str`
     s[1usize] = bot();
     //~^ ERROR `core::ops::Index<usize>` is not implemented for the type `str`
-    //~^^ ERROR `core::ops::Index<usize>` is not implemented for the type `str`
+    //~| ERROR `core::ops::IndexMut<usize>` is not implemented for the type `str`
+    //~| ERROR `core::ops::Index<usize>` is not implemented for the type `str`
 }
 
 pub fn main() {}