diff --git a/src/libunicode/lib.rs b/src/libunicode/lib.rs
index 66cd22dfb08..1f75daa7bde 100644
--- a/src/libunicode/lib.rs
+++ b/src/libunicode/lib.rs
@@ -29,6 +29,7 @@
        html_playground_url = "http://play.rust-lang.org/")]
 #![no_std]
 #![feature(globs)]
+#![feature(unboxed_closures)]
 
 extern crate core;
 
diff --git a/src/libunicode/u_str.rs b/src/libunicode/u_str.rs
index 33e4df3ca36..80311137b01 100644
--- a/src/libunicode/u_str.rs
+++ b/src/libunicode/u_str.rs
@@ -29,7 +29,7 @@ use tables::grapheme::GraphemeCat;
 
 /// An iterator over the words of a string, separated by a sequence of whitespace
 /// FIXME: This should be opaque
-pub type Words<'a> = Filter<&'a str, CharSplits<'a, |char|:'a -> bool>, fn(&&str) -> bool>;
+pub type Words<'a> = Filter<&'a str, CharSplits<'a, fn(char) -> bool>, fn(&&str) -> bool>;
 
 /// Methods for Unicode string slices
 pub trait UnicodeStrPrelude for Sized? {
@@ -143,8 +143,9 @@ impl UnicodeStrPrelude for str {
     #[inline]
     fn words(&self) -> Words {
         fn is_not_empty(s: &&str) -> bool { !s.is_empty() }
-        let f = |c: char| c.is_whitespace();
-        self.split(f).filter(is_not_empty)
+        fn is_whitespace(c: char) -> bool { c.is_whitespace() }
+
+        self.split(is_whitespace).filter(is_not_empty)
     }
 
     #[inline]
@@ -165,12 +166,12 @@ impl UnicodeStrPrelude for str {
 
     #[inline]
     fn trim_left(&self) -> &str {
-        self.trim_left_chars(|c: char| c.is_whitespace())
+        self.trim_left_chars(|&: c: char| c.is_whitespace())
     }
 
     #[inline]
     fn trim_right(&self) -> &str {
-        self.trim_right_chars(|c: char| c.is_whitespace())
+        self.trim_right_chars(|&: c: char| c.is_whitespace())
     }
 }