diff --git a/src/libcollections/hashmap.rs b/src/libcollections/hashmap.rs
index 42b57a1ea406..7292f9c47d79 100644
--- a/src/libcollections/hashmap.rs
+++ b/src/libcollections/hashmap.rs
@@ -2013,8 +2013,8 @@ mod test_map {
 
         let map_str = format!("{}", map);
 
-        assert!(map_str == "{1: 2, 3: 4}".to_owned() || map_str == "{3: 4, 1: 2}".to_owned());
-        assert_eq!(format!("{}", empty), "{}".to_owned());
+        assert!(map_str == "{1: 2, 3: 4}".to_string() || map_str == "{3: 4, 1: 2}".to_string());
+        assert_eq!(format!("{}", empty), "{}".to_string());
     }
 
     #[test]
diff --git a/src/libcollections/treemap.rs b/src/libcollections/treemap.rs
index fb663d91131a..1ba5fd42bfc7 100644
--- a/src/libcollections/treemap.rs
+++ b/src/libcollections/treemap.rs
@@ -1366,8 +1366,8 @@ mod test_treemap {
 
         let map_str = format!("{}", map);
 
-        assert!(map_str == "{1: 2, 3: 4}".to_owned());
-        assert_eq!(format!("{}", empty), "{}".to_owned());
+        assert!(map_str == "{1: 2, 3: 4}".to_string());
+        assert_eq!(format!("{}", empty), "{}".to_string());
     }
 
     #[test]
@@ -1776,7 +1776,7 @@ mod test_set {
 
         let set_str = format!("{}", set);
 
-        assert!(set_str == "{1, 2}".to_owned());
-        assert_eq!(format!("{}", empty), "{}".to_owned());
+        assert!(set_str == "{1, 2}".to_string());
+        assert_eq!(format!("{}", empty), "{}".to_string());
     }
 }
diff --git a/src/libdebug/repr.rs b/src/libdebug/repr.rs
index 6807e73982d7..67eee6f2ecf0 100644
--- a/src/libdebug/repr.rs
+++ b/src/libdebug/repr.rs
@@ -613,7 +613,7 @@ fn test_repr() {
     fn exact_test<T>(t: &T, e:&str) {
         let mut m = io::MemWriter::new();
         write_repr(&mut m as &mut io::Writer, t).unwrap();
-        let s = str::from_utf8(m.unwrap().as_slice()).unwrap().to_owned();
+        let s = str::from_utf8(m.unwrap().as_slice()).unwrap().to_string();
         assert_eq!(s.as_slice(), e);
     }