diff --git a/src/libstd/sync/mpsc/mod.rs b/src/libstd/sync/mpsc/mod.rs
index 7adfd9154ac..48629beafc8 100644
--- a/src/libstd/sync/mpsc/mod.rs
+++ b/src/libstd/sync/mpsc/mod.rs
@@ -342,7 +342,7 @@ mod spsc_queue;
 /// The receiving-half of Rust's channel type. This half can only be owned by
 /// one task
 #[stable(feature = "rust1", since = "1.0.0")]
-pub struct Receiver<T> {
+pub struct Receiver<T:Send> {
     inner: UnsafeCell<Flavor<T>>,
 }
 
@@ -354,14 +354,14 @@ unsafe impl<T: Send> Send for Receiver<T> { }
 /// whenever `next` is called, waiting for a new message, and `None` will be
 /// returned when the corresponding channel has hung up.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub struct Iter<'a, T:'a> {
+pub struct Iter<'a, T:Send+'a> {
     rx: &'a Receiver<T>
 }
 
 /// The sending-half of Rust's asynchronous channel type. This half can only be
 /// owned by one task, but it can be cloned to send to other tasks.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub struct Sender<T> {
+pub struct Sender<T:Send> {
     inner: UnsafeCell<Flavor<T>>,
 }
 
@@ -433,7 +433,7 @@ pub enum TrySendError<T> {
     Disconnected(T),
 }
 
-enum Flavor<T> {
+enum Flavor<T:Send> {
     Oneshot(Arc<UnsafeCell<oneshot::Packet<T>>>),
     Stream(Arc<UnsafeCell<stream::Packet<T>>>),
     Shared(Arc<UnsafeCell<shared::Packet<T>>>),
@@ -441,7 +441,7 @@ enum Flavor<T> {
 }
 
 #[doc(hidden)]
-trait UnsafeFlavor<T> {
+trait UnsafeFlavor<T:Send> {
     fn inner_unsafe<'a>(&'a self) -> &'a UnsafeCell<Flavor<T>>;
     unsafe fn inner_mut<'a>(&'a self) -> &'a mut Flavor<T> {
         &mut *self.inner_unsafe().get()
@@ -450,12 +450,12 @@ trait UnsafeFlavor<T> {
         &*self.inner_unsafe().get()
     }
 }
-impl<T> UnsafeFlavor<T> for Sender<T> {
+impl<T:Send> UnsafeFlavor<T> for Sender<T> {
     fn inner_unsafe<'a>(&'a self) -> &'a UnsafeCell<Flavor<T>> {
         &self.inner
     }
 }
-impl<T> UnsafeFlavor<T> for Receiver<T> {
+impl<T:Send> UnsafeFlavor<T> for Receiver<T> {
     fn inner_unsafe<'a>(&'a self) -> &'a UnsafeCell<Flavor<T>> {
         &self.inner
     }
diff --git a/src/libstd/sync/mpsc/oneshot.rs b/src/libstd/sync/mpsc/oneshot.rs
index f287712d9d4..13578ce0517 100644
--- a/src/libstd/sync/mpsc/oneshot.rs
+++ b/src/libstd/sync/mpsc/oneshot.rs
@@ -54,7 +54,7 @@ const DISCONNECTED: usize = 2;   // channel is disconnected OR upgraded
 // moves *from* a pointer, ownership of the token is transferred to
 // whoever changed the state.
 
-pub struct Packet<T> {
+pub struct Packet<T:Send> {
     // Internal state of the chan/port pair (stores the blocked task as well)
     state: AtomicUsize,
     // One-shot data slot location
@@ -64,7 +64,7 @@ pub struct Packet<T> {
     upgrade: MyUpgrade<T>,
 }
 
-pub enum Failure<T> {
+pub enum Failure<T:Send> {
     Empty,
     Disconnected,
     Upgraded(Receiver<T>),
@@ -76,13 +76,13 @@ pub enum UpgradeResult {
     UpWoke(SignalToken),
 }
 
-pub enum SelectionResult<T> {
+pub enum SelectionResult<T:Send> {
     SelCanceled,
     SelUpgraded(SignalToken, Receiver<T>),
     SelSuccess,
 }
 
-enum MyUpgrade<T> {
+enum MyUpgrade<T:Send> {
     NothingSent,
     SendUsed,
     GoUp(Receiver<T>),
diff --git a/src/libstd/sync/mpsc/select.rs b/src/libstd/sync/mpsc/select.rs
index 0f936641cdc..b509b3472ee 100644
--- a/src/libstd/sync/mpsc/select.rs
+++ b/src/libstd/sync/mpsc/select.rs
@@ -80,7 +80,7 @@ impl !marker::Send for Select {}
 /// A handle to a receiver which is currently a member of a `Select` set of
 /// receivers.  This handle is used to keep the receiver in the set as well as
 /// interact with the underlying receiver.
-pub struct Handle<'rx, T:'rx> {
+pub struct Handle<'rx, T:Send+'rx> {
     /// The ID of this handle, used to compare against the return value of
     /// `Select::wait()`
     id: usize,
diff --git a/src/libstd/sync/mpsc/stream.rs b/src/libstd/sync/mpsc/stream.rs
index 5a1e05f9c15..a5a73314a6d 100644
--- a/src/libstd/sync/mpsc/stream.rs
+++ b/src/libstd/sync/mpsc/stream.rs
@@ -39,7 +39,7 @@ const MAX_STEALS: isize = 5;
 #[cfg(not(test))]
 const MAX_STEALS: isize = 1 << 20;
 
-pub struct Packet<T> {
+pub struct Packet<T:Send> {
     queue: spsc::Queue<Message<T>>, // internal queue for all message
 
     cnt: AtomicIsize, // How many items are on this channel
@@ -49,7 +49,7 @@ pub struct Packet<T> {
     port_dropped: AtomicBool, // flag if the channel has been destroyed.
 }
 
-pub enum Failure<T> {
+pub enum Failure<T:Send> {
     Empty,
     Disconnected,
     Upgraded(Receiver<T>),
@@ -61,7 +61,7 @@ pub enum UpgradeResult {
     UpWoke(SignalToken),
 }
 
-pub enum SelectionResult<T> {
+pub enum SelectionResult<T:Send> {
     SelSuccess,
     SelCanceled,
     SelUpgraded(SignalToken, Receiver<T>),
@@ -69,7 +69,7 @@ pub enum SelectionResult<T> {
 
 // Any message could contain an "upgrade request" to a new shared port, so the
 // internal queue it's a queue of T, but rather Message<T>
-enum Message<T> {
+enum Message<T:Send> {
     Data(T),
     GoUp(Receiver<T>),
 }
diff --git a/src/libstd/sys/common/helper_thread.rs b/src/libstd/sys/common/helper_thread.rs
index 2a852fbcd57..e8bec66d987 100644
--- a/src/libstd/sys/common/helper_thread.rs
+++ b/src/libstd/sys/common/helper_thread.rs
@@ -38,7 +38,7 @@ use thread;
 ///
 /// The fields of this helper are all public, but they should not be used, this
 /// is for static initialization.
-pub struct Helper<M> {
+pub struct Helper<M:Send> {
     /// Internal lock which protects the remaining fields
     pub lock: StaticMutex,
     pub cond: StaticCondvar,