diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index 0705af86..51981869 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -70,9 +70,11 @@ use super::{
     Error,
     Serialize,
     Serializer,
-    IteratorSerializer,
 };
 
+#[cfg(feature = "unstable")]
+use super::IteratorSerializer;
+
 ///////////////////////////////////////////////////////////////////////////////
 
 macro_rules! impl_visit {
diff --git a/serde/src/ser/mod.rs b/serde/src/ser/mod.rs
index ab6d08fa..97784ef0 100644
--- a/serde/src/ser/mod.rs
+++ b/serde/src/ser/mod.rs
@@ -18,7 +18,9 @@ use error;
 #[cfg(all(feature = "collections", not(feature = "std")))]
 use collections::String;
 
+#[cfg(feature = "unstable")]
 use core::marker::PhantomData;
+#[cfg(feature = "unstable")]
 use core::cell::RefCell;
 
 pub mod impls;
@@ -418,12 +420,14 @@ pub trait Serializer {
 /// A wrapper type for iterators that implements `Serialize` for iterators whose items implement
 /// `Serialize`. Don't use multiple times. Create new versions of this with the `iterator` function
 /// every time you want to serialize an iterator.
+#[cfg(feature = "unstable")]
 pub struct IteratorSerializer<I>(RefCell<Option<I>>)
     where <I as Iterator>::Item: Serialize,
           I: Iterator;
 
 /// Creates a temporary type that can be passed to any function expecting a `Serialize` and will
 /// serialize the given iterator as a sequence
+#[cfg(feature = "unstable")]
 pub fn iterator<I>(iter: I) -> IteratorSerializer<I>
     where <I as Iterator>::Item: Serialize,
           I: Iterator
diff --git a/testing/tests/test_ser.rs b/testing/tests/test_ser.rs
index 02943fab..5d54b432 100644
--- a/testing/tests/test_ser.rs
+++ b/testing/tests/test_ser.rs
@@ -15,6 +15,7 @@ use self::serde_test::{
 extern crate fnv;
 use self::fnv::FnvHasher;
 
+#[cfg(feature = "unstable")]
 use serde::ser::iterator;
 
 //////////////////////////////////////////////////////////////////////////
@@ -100,45 +101,6 @@ declare_ser_tests! {
             Token::I32(1),
         ],
     }
-    test_iterator {
-        iterator([0; 0].iter()) => &[
-            Token::SeqStart(Some(0)),
-            Token::SeqEnd,
-        ],
-        iterator([1, 2, 3].iter()) => &[
-            Token::SeqStart(Some(3)),
-                Token::SeqSep,
-                Token::I32(1),
-
-                Token::SeqSep,
-                Token::I32(2),
-
-                Token::SeqSep,
-                Token::I32(3),
-            Token::SeqEnd,
-        ],
-        iterator([1, 2, 3].iter().map(|x| x * 2)) => &[
-            Token::SeqStart(Some(3)),
-                Token::SeqSep,
-                Token::I32(2),
-
-                Token::SeqSep,
-                Token::I32(4),
-
-                Token::SeqSep,
-                Token::I32(6),
-            Token::SeqEnd,
-        ],
-        iterator([1, 2, 3].iter().filter(|&x| x % 2 != 0)) => &[
-            Token::SeqStart(None),
-                Token::SeqSep,
-                Token::I32(1),
-
-                Token::SeqSep,
-                Token::I32(3),
-            Token::SeqEnd,
-        ],
-    }
     test_slice {
         &[0][..0] => &[
             Token::SeqStart(Some(0)),
@@ -410,6 +372,49 @@ declare_ser_tests! {
     }
 }
 
+
+#[cfg(feature = "unstable")]
+#[test]
+fn test_iterator() {
+    assert_ser_tokens(iterator([0; 0].iter()), &[
+        Token::SeqStart(Some(0)),
+        Token::SeqEnd,
+    ]);
+    assert_ser_tokens(iterator([1, 2, 3].iter()), &[
+        Token::SeqStart(Some(3)),
+            Token::SeqSep,
+            Token::I32(1),
+
+            Token::SeqSep,
+            Token::I32(2),
+
+            Token::SeqSep,
+            Token::I32(3),
+        Token::SeqEnd,
+    ]);
+    assert_ser_tokens(iterator([1, 2, 3].iter().map(|x| x * 2)), &[
+        Token::SeqStart(Some(3)),
+            Token::SeqSep,
+            Token::I32(2),
+
+            Token::SeqSep,
+            Token::I32(4),
+
+            Token::SeqSep,
+            Token::I32(6),
+        Token::SeqEnd,
+    ]);
+    assert_ser_tokens(iterator([1, 2, 3].iter().filter(|&x| x % 2 != 0)), &[
+        Token::SeqStart(None),
+            Token::SeqSep,
+            Token::I32(1),
+
+            Token::SeqSep,
+            Token::I32(3),
+        Token::SeqEnd,
+    ]);
+}
+
 #[cfg(feature = "unstable")]
 #[test]
 fn test_net_ipaddr() {