diff --git a/src/libcore/iterator.rs b/src/libcore/iterator.rs
index 40c9637f692..3811d28b030 100644
--- a/src/libcore/iterator.rs
+++ b/src/libcore/iterator.rs
@@ -45,6 +45,7 @@ fn scan<'r, St, B>(self, initial_state: St, f: &'r fn(&mut St, A) -> Option<B>)
     fn advance(&mut self, f: &fn(A) -> bool);
     #[cfg(not(stage0))]
     fn advance(&mut self, f: &fn(A) -> bool) -> bool;
+    fn to_vec(self) -> ~[A];
 }
 
 /// Iterator adaptors provided for every `Iterator` implementation. The adaptor objects are also
@@ -131,6 +132,14 @@ fn advance(&mut self, f: &fn(A) -> bool) -> bool {
             }
         }
     }
+
+    #[inline(always)]
+    fn to_vec(self) -> ~[A] {
+        let mut v = ~[];
+        let mut it = self;
+        for it.advance() |x| { v.push(x); }
+        return v;
+    }
 }
 
 pub struct ChainIterator<T, U> {