diff --git a/src/libcollections/binary_heap.rs b/src/libcollections/binary_heap.rs
index 6196d94b5a6..2f994e94ccc 100644
--- a/src/libcollections/binary_heap.rs
+++ b/src/libcollections/binary_heap.rs
@@ -677,7 +677,8 @@ impl<'a, T> IntoIterator for &'a BinaryHeap<T> where T: Ord {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Ord> Extend<T> for BinaryHeap<T> {
-    fn extend<Iter: Iterator<Item=T>>(&mut self, iter: Iter) {
+    fn extend<I: IntoIterator<Item=T>>(&mut self, iterable: I) {
+        let iter = iterable.into_iter();
         let (lower, _) = iter.size_hint();
 
         self.reserve(lower);
diff --git a/src/libcollections/bit.rs b/src/libcollections/bit.rs
index a2e36155933..c1d79d82043 100644
--- a/src/libcollections/bit.rs
+++ b/src/libcollections/bit.rs
@@ -934,7 +934,8 @@ impl FromIterator<bool> for BitVec {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Extend<bool> for BitVec {
     #[inline]
-    fn extend<I: Iterator<Item=bool>>(&mut self, iterator: I) {
+    fn extend<I: IntoIterator<Item=bool>>(&mut self, iterable: I) {
+        let iterator = iterable.into_iter();
         let (min, _) = iterator.size_hint();
         self.reserve(min);
         for element in iterator {
@@ -1143,8 +1144,8 @@ impl FromIterator<usize> for BitSet {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Extend<usize> for BitSet {
     #[inline]
-    fn extend<I: Iterator<Item=usize>>(&mut self, iterator: I) {
-        for i in iterator {
+    fn extend<I: IntoIterator<Item=usize>>(&mut self, iter: I) {
+        for i in iter {
             self.insert(i);
         }
     }
diff --git a/src/libcollections/btree/map.rs b/src/libcollections/btree/map.rs
index 96052156df0..9273d50db85 100644
--- a/src/libcollections/btree/map.rs
+++ b/src/libcollections/btree/map.rs
@@ -836,7 +836,7 @@ impl<K: Ord, V> FromIterator<(K, V)> for BTreeMap<K, V> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<K: Ord, V> Extend<(K, V)> for BTreeMap<K, V> {
     #[inline]
-    fn extend<T: Iterator<Item=(K, V)>>(&mut self, iter: T) {
+    fn extend<T: IntoIterator<Item=(K, V)>>(&mut self, iter: T) {
         for (k, v) in iter {
             self.insert(k, v);
         }
diff --git a/src/libcollections/btree/set.rs b/src/libcollections/btree/set.rs
index 7ef887b70cc..d2241a67464 100644
--- a/src/libcollections/btree/set.rs
+++ b/src/libcollections/btree/set.rs
@@ -503,7 +503,7 @@ impl<'a, T> IntoIterator for &'a BTreeSet<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Ord> Extend<T> for BTreeSet<T> {
     #[inline]
-    fn extend<Iter: Iterator<Item=T>>(&mut self, iter: Iter) {
+    fn extend<Iter: IntoIterator<Item=T>>(&mut self, iter: Iter) {
         for elem in iter {
             self.insert(elem);
         }
diff --git a/src/libcollections/enum_set.rs b/src/libcollections/enum_set.rs
index d5403ca5d9b..3f8c0121faf 100644
--- a/src/libcollections/enum_set.rs
+++ b/src/libcollections/enum_set.rs
@@ -268,8 +268,8 @@ impl<'a, E> IntoIterator for &'a EnumSet<E> where E: CLike {
 }
 
 impl<E:CLike> Extend<E> for EnumSet<E> {
-    fn extend<I: Iterator<Item=E>>(&mut self, iterator: I) {
-        for element in iterator {
+    fn extend<I: IntoIterator<Item=E>>(&mut self, iter: I) {
+        for element in iter {
             self.insert(element);
         }
     }
diff --git a/src/libcollections/linked_list.rs b/src/libcollections/linked_list.rs
index 550c1450b93..0ec1371c73c 100644
--- a/src/libcollections/linked_list.rs
+++ b/src/libcollections/linked_list.rs
@@ -872,8 +872,8 @@ impl<'a, T> IntoIterator for &'a mut LinkedList<T> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A> Extend<A> for LinkedList<A> {
-    fn extend<T: Iterator<Item=A>>(&mut self, iterator: T) {
-        for elt in iterator { self.push_back(elt); }
+    fn extend<T: IntoIterator<Item=A>>(&mut self, iter: T) {
+        for elt in iter { self.push_back(elt); }
     }
 }
 
diff --git a/src/libcollections/string.rs b/src/libcollections/string.rs
index 69fd28d1723..dc1158ecaf8 100644
--- a/src/libcollections/string.rs
+++ b/src/libcollections/string.rs
@@ -21,7 +21,7 @@ use core::default::Default;
 use core::error::Error;
 use core::fmt;
 use core::hash;
-use core::iter::FromIterator;
+use core::iter::{IntoIterator, FromIterator};
 use core::mem;
 use core::ops::{self, Deref, Add, Index};
 use core::ptr;
@@ -728,7 +728,8 @@ impl<'a> FromIterator<&'a str> for String {
 #[unstable(feature = "collections",
            reason = "waiting on Extend stabilization")]
 impl Extend<char> for String {
-    fn extend<I:Iterator<Item=char>>(&mut self, iterator: I) {
+    fn extend<I: IntoIterator<Item=char>>(&mut self, iterable: I) {
+        let iterator = iterable.into_iter();
         let (lower_bound, _) = iterator.size_hint();
         self.reserve(lower_bound);
         for ch in iterator {
@@ -740,7 +741,8 @@ impl Extend<char> for String {
 #[unstable(feature = "collections",
            reason = "waiting on Extend stabilization")]
 impl<'a> Extend<&'a str> for String {
-    fn extend<I: Iterator<Item=&'a str>>(&mut self, iterator: I) {
+    fn extend<I: IntoIterator<Item=&'a str>>(&mut self, iterable: I) {
+        let iterator = iterable.into_iter();
         // A guess that at least one byte per iterator element will be needed.
         let (lower_bound, _) = iterator.size_hint();
         self.reserve(lower_bound);
diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index bde733644b5..e4b090e4dd7 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -1480,7 +1480,8 @@ impl<'a, T> IntoIterator for &'a mut Vec<T> {
 #[unstable(feature = "collections", reason = "waiting on Extend stability")]
 impl<T> Extend<T> for Vec<T> {
     #[inline]
-    fn extend<I: Iterator<Item=T>>(&mut self, iterator: I) {
+    fn extend<I: IntoIterator<Item=T>>(&mut self, iterable: I) {
+        let iterator = iterable.into_iter();
         let (lower, _) = iterator.size_hint();
         self.reserve(lower);
         for element in iterator {
diff --git a/src/libcollections/vec_deque.rs b/src/libcollections/vec_deque.rs
index 76b2d5b968e..cc01e800f60 100644
--- a/src/libcollections/vec_deque.rs
+++ b/src/libcollections/vec_deque.rs
@@ -1741,8 +1741,8 @@ impl<'a, T> IntoIterator for &'a mut VecDeque<T> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A> Extend<A> for VecDeque<A> {
-    fn extend<T: Iterator<Item=A>>(&mut self, iterator: T) {
-        for elt in iterator {
+    fn extend<T: IntoIterator<Item=A>>(&mut self, iter: T) {
+        for elt in iter {
             self.push_back(elt);
         }
     }
diff --git a/src/libcollections/vec_map.rs b/src/libcollections/vec_map.rs
index 82ccfd0614f..7085111d6a8 100644
--- a/src/libcollections/vec_map.rs
+++ b/src/libcollections/vec_map.rs
@@ -700,7 +700,7 @@ impl<'a, T> IntoIterator for &'a mut VecMap<T> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<V> Extend<(usize, V)> for VecMap<V> {
-    fn extend<Iter: Iterator<Item=(usize, V)>>(&mut self, iter: Iter) {
+    fn extend<I: IntoIterator<Item=(usize, V)>>(&mut self, iter: I) {
         for (k, v) in iter {
             self.insert(k, v);
         }
diff --git a/src/libcore/iter.rs b/src/libcore/iter.rs
index fffba1561a3..2e9977cd3eb 100644
--- a/src/libcore/iter.rs
+++ b/src/libcore/iter.rs
@@ -147,7 +147,7 @@ impl<I: Iterator> IntoIterator for I {
 pub trait Extend<A> {
     /// Extend a container with the elements yielded by an arbitrary iterator
     #[stable(feature = "rust1", since = "1.0.0")]
-    fn extend<T: Iterator<Item=A>>(&mut self, iterator: T);
+    fn extend<T: IntoIterator<Item=A>>(&mut self, iterable: T);
 }
 
 /// An extension trait providing numerous methods applicable to all iterators.
diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index 1b9f8b99017..61b531054a0 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -1570,7 +1570,7 @@ impl<K, V, S, H> Extend<(K, V)> for HashMap<K, V, S>
           S: HashState<Hasher=H>,
           H: hash::Hasher<Output=u64>
 {
-    fn extend<T: Iterator<Item=(K, V)>>(&mut self, iter: T) {
+    fn extend<T: IntoIterator<Item=(K, V)>>(&mut self, iter: T) {
         for (k, v) in iter {
             self.insert(k, v);
         }
diff --git a/src/libstd/collections/hash/set.rs b/src/libstd/collections/hash/set.rs
index 5fbbcb3b347..f5e57b78d2a 100644
--- a/src/libstd/collections/hash/set.rs
+++ b/src/libstd/collections/hash/set.rs
@@ -636,7 +636,7 @@ impl<T, S, H> Extend<T> for HashSet<T, S>
           S: HashState<Hasher=H>,
           H: hash::Hasher<Output=u64>
 {
-    fn extend<I: Iterator<Item=T>>(&mut self, iter: I) {
+    fn extend<I: IntoIterator<Item=T>>(&mut self, iter: I) {
         for k in iter {
             self.insert(k);
         }
diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index 1d992668900..f25cc83b93e 100755
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -110,7 +110,7 @@ use core::prelude::*;
 use ascii::*;
 use borrow::BorrowFrom;
 use cmp;
-use iter;
+use iter::{self, IntoIterator};
 use mem;
 use ops::{self, Deref};
 use string::CowString;
@@ -961,7 +961,7 @@ impl<'a, P: ?Sized + 'a> iter::FromIterator<&'a P> for PathBuf where P: AsPath {
 }
 
 impl<'a, P: ?Sized + 'a> iter::Extend<&'a P> for PathBuf where P: AsPath {
-    fn extend<I: Iterator<Item = &'a P>>(&mut self, iter: I) {
+    fn extend<I: IntoIterator<Item = &'a P>>(&mut self, iter: I) {
         for p in iter {
             self.push(p)
         }
diff --git a/src/libstd/sys/common/wtf8.rs b/src/libstd/sys/common/wtf8.rs
index b610f6c370b..e7cb67c6287 100644
--- a/src/libstd/sys/common/wtf8.rs
+++ b/src/libstd/sys/common/wtf8.rs
@@ -32,7 +32,7 @@ use borrow::Cow;
 use cmp;
 use fmt;
 use hash::{Hash, Writer, Hasher};
-use iter::FromIterator;
+use iter::{FromIterator, IntoIterator};
 use mem;
 use num::Int;
 use ops;
@@ -368,7 +368,8 @@ impl FromIterator<CodePoint> for Wtf8Buf {
 /// This replaces surrogate code point pairs with supplementary code points,
 /// like concatenating ill-formed UTF-16 strings effectively would.
 impl Extend<CodePoint> for Wtf8Buf {
-    fn extend<T: Iterator<Item=CodePoint>>(&mut self, iterator: T) {
+    fn extend<T: IntoIterator<Item=CodePoint>>(&mut self, iterable: T) {
+        let iterator = iterable.into_iter();
         let (low, _high) = iterator.size_hint();
         // Lower bound of one byte per code point (ASCII only)
         self.bytes.reserve(low);
diff --git a/src/libsyntax/util/small_vector.rs b/src/libsyntax/util/small_vector.rs
index b2009a7e848..6a1fb4008ad 100644
--- a/src/libsyntax/util/small_vector.rs
+++ b/src/libsyntax/util/small_vector.rs
@@ -11,7 +11,7 @@
 use self::SmallVectorRepr::*;
 use self::IntoIterRepr::*;
 
-use std::iter::FromIterator;
+use std::iter::{IntoIterator, FromIterator};
 use std::mem;
 use std::slice;
 use std::vec;
@@ -38,7 +38,7 @@ impl<T> FromIterator<T> for SmallVector<T> {
 }
 
 impl<T> Extend<T> for SmallVector<T> {
-    fn extend<I: Iterator<Item=T>>(&mut self, iter: I) {
+    fn extend<I: IntoIterator<Item=T>>(&mut self, iter: I) {
         for val in iter {
             self.push(val);
         }