diff --git a/core/src/lib.rs b/core/src/lib.rs
index e296c8d2..a2ac1b34 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -61,6 +61,7 @@
 
 /// Multi-address re-export.
 pub use multiaddr;
+pub use multistream_select::Negotiated;
 
 mod keys_proto;
 mod peer_id;
diff --git a/core/src/protocols_handler/one_shot.rs b/core/src/protocols_handler/one_shot.rs
index c0a50456..88601125 100644
--- a/core/src/protocols_handler/one_shot.rs
+++ b/core/src/protocols_handler/one_shot.rs
@@ -188,7 +188,7 @@ where
             self.pending_error = Some(error);
         }
     }
- 
+
     #[inline]
     fn connection_keep_alive(&self) -> KeepAlive {
         self.keep_alive
diff --git a/core/src/upgrade/denied.rs b/core/src/upgrade/denied.rs
index d1de858e..9dec47ee 100644
--- a/core/src/upgrade/denied.rs
+++ b/core/src/upgrade/denied.rs
@@ -20,6 +20,7 @@
 
 use crate::upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo};
 use futures::future;
+use multistream_select::Negotiated;
 use std::iter;
 use void::Void;
 
@@ -42,7 +43,7 @@ impl<C> InboundUpgrade<C> for DeniedUpgrade {
     type Error = Void;
     type Future = future::Empty<Self::Output, Self::Error>;
 
-    fn upgrade_inbound(self, _: C, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, _: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::empty()
     }
 }
@@ -52,7 +53,7 @@ impl<C> OutboundUpgrade<C> for DeniedUpgrade {
     type Error = Void;
     type Future = future::Empty<Self::Output, Self::Error>;
 
-    fn upgrade_outbound(self, _: C, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, _: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::empty()
     }
 }
diff --git a/core/src/upgrade/either.rs b/core/src/upgrade/either.rs
index 28db987c..bf3d86b8 100644
--- a/core/src/upgrade/either.rs
+++ b/core/src/upgrade/either.rs
@@ -22,6 +22,7 @@ use crate::{
     either::{EitherOutput, EitherError, EitherFuture2, EitherName},
     upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo}
 };
+use multistream_select::Negotiated;
 
 /// A type to represent two possible upgrade types (inbound or outbound).
 #[derive(Debug, Clone)]
@@ -55,7 +56,7 @@ where
     type Error = EitherError<EA, EB>;
     type Future = EitherFuture2<A::Future, B::Future>;
 
-    fn upgrade_inbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         match (self, info) {
             (EitherUpgrade::A(a), EitherName::A(info)) => EitherFuture2::A(a.upgrade_inbound(sock, info)),
             (EitherUpgrade::B(b), EitherName::B(info)) => EitherFuture2::B(b.upgrade_inbound(sock, info)),
@@ -73,7 +74,7 @@ where
     type Error = EitherError<EA, EB>;
     type Future = EitherFuture2<A::Future, B::Future>;
 
-    fn upgrade_outbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         match (self, info) {
             (EitherUpgrade::A(a), EitherName::A(info)) => EitherFuture2::A(a.upgrade_outbound(sock, info)),
             (EitherUpgrade::B(b), EitherName::B(info)) => EitherFuture2::B(b.upgrade_outbound(sock, info)),
diff --git a/core/src/upgrade/map.rs b/core/src/upgrade/map.rs
index d8415b5f..ee17b845 100644
--- a/core/src/upgrade/map.rs
+++ b/core/src/upgrade/map.rs
@@ -20,6 +20,7 @@
 
 use crate::upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo};
 use futures::{prelude::*, try_ready};
+use multistream_select::Negotiated;
 
 /// Wraps around an upgrade and applies a closure to the output.
 #[derive(Debug, Clone)]
@@ -52,7 +53,7 @@ where
     type Error = U::Error;
     type Future = MapFuture<U::Future, F>;
 
-    fn upgrade_inbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         MapFuture {
             inner: self.upgrade.upgrade_inbound(sock, info),
             map: Some(self.fun)
@@ -68,7 +69,7 @@ where
     type Error = U::Error;
     type Future = U::Future;
 
-    fn upgrade_outbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         self.upgrade.upgrade_outbound(sock, info)
     }
 }
@@ -103,7 +104,7 @@ where
     type Error = U::Error;
     type Future = U::Future;
 
-    fn upgrade_inbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         self.upgrade.upgrade_inbound(sock, info)
     }
 }
@@ -117,7 +118,7 @@ where
     type Error = U::Error;
     type Future = MapFuture<U::Future, F>;
 
-    fn upgrade_outbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         MapFuture {
             inner: self.upgrade.upgrade_outbound(sock, info),
             map: Some(self.fun)
@@ -156,7 +157,7 @@ where
     type Error = T;
     type Future = MapErrFuture<U::Future, F>;
 
-    fn upgrade_inbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         MapErrFuture {
             fut: self.upgrade.upgrade_inbound(sock, info),
             fun: Some(self.fun)
@@ -172,7 +173,7 @@ where
     type Error = U::Error;
     type Future = U::Future;
 
-    fn upgrade_outbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         self.upgrade.upgrade_outbound(sock, info)
     }
 }
@@ -208,7 +209,7 @@ where
     type Error = T;
     type Future = MapErrFuture<U::Future, F>;
 
-    fn upgrade_outbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         MapErrFuture {
             fut: self.upgrade.upgrade_outbound(sock, info),
             fun: Some(self.fun)
@@ -224,7 +225,7 @@ where
     type Error = U::Error;
     type Future = U::Future;
 
-    fn upgrade_inbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         self.upgrade.upgrade_inbound(sock, info)
     }
 }
diff --git a/core/src/upgrade/mod.rs b/core/src/upgrade/mod.rs
index 50032bd3..e3087745 100644
--- a/core/src/upgrade/mod.rs
+++ b/core/src/upgrade/mod.rs
@@ -67,6 +67,7 @@ mod transfer;
 
 use futures::future::Future;
 
+pub use multistream_select::Negotiated;
 pub use self::{
     apply::{apply, apply_inbound, apply_outbound, InboundUpgradeApply, OutboundUpgradeApply},
     denied::DeniedUpgrade,
@@ -114,7 +115,7 @@ pub trait InboundUpgrade<C>: UpgradeInfo {
     /// method is called to start the handshake.
     ///
     /// The `info` is the identifier of the protocol, as produced by `protocol_info`.
-    fn upgrade_inbound(self, socket: C, info: Self::Info) -> Self::Future;
+    fn upgrade_inbound(self, socket: Negotiated<C>, info: Self::Info) -> Self::Future;
 }
 
 /// Extension trait for `InboundUpgrade`. Automatically implemented on all types that implement
@@ -154,7 +155,7 @@ pub trait OutboundUpgrade<C>: UpgradeInfo {
     /// method is called to start the handshake.
     ///
     /// The `info` is the identifier of the protocol, as produced by `protocol_info`.
-    fn upgrade_outbound(self, socket: C, info: Self::Info) -> Self::Future;
+    fn upgrade_outbound(self, socket: Negotiated<C>, info: Self::Info) -> Self::Future;
 }
 
 /// Extention trait for `OutboundUpgrade`. Automatically implemented on all types that implement
diff --git a/core/src/upgrade/select.rs b/core/src/upgrade/select.rs
index 8fa4c5b8..61c3ec5e 100644
--- a/core/src/upgrade/select.rs
+++ b/core/src/upgrade/select.rs
@@ -22,6 +22,7 @@ use crate::{
     either::{EitherOutput, EitherError, EitherFuture2, EitherName},
     upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo}
 };
+use multistream_select::Negotiated;
 
 /// Upgrade that combines two upgrades into one. Supports all the protocols supported by either
 /// sub-upgrade.
@@ -64,7 +65,7 @@ where
     type Error = EitherError<EA, EB>;
     type Future = EitherFuture2<A::Future, B::Future>;
 
-    fn upgrade_inbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         match info {
             EitherName::A(info) => EitherFuture2::A(self.0.upgrade_inbound(sock, info)),
             EitherName::B(info) => EitherFuture2::B(self.1.upgrade_inbound(sock, info))
@@ -81,7 +82,7 @@ where
     type Error = EitherError<EA, EB>;
     type Future = EitherFuture2<A::Future, B::Future>;
 
-    fn upgrade_outbound(self, sock: C, info: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, sock: Negotiated<C>, info: Self::Info) -> Self::Future {
         match info {
             EitherName::A(info) => EitherFuture2::A(self.0.upgrade_outbound(sock, info)),
             EitherName::B(info) => EitherFuture2::B(self.1.upgrade_outbound(sock, info))
diff --git a/misc/multistream-select/src/dialer_select.rs b/misc/multistream-select/src/dialer_select.rs
index 8e591168..bbd40c1a 100644
--- a/misc/multistream-select/src/dialer_select.rs
+++ b/misc/multistream-select/src/dialer_select.rs
@@ -31,7 +31,7 @@ use crate::protocol::{
 use log::trace;
 use std::mem;
 use tokio_io::{AsyncRead, AsyncWrite};
-use crate::ProtocolChoiceError;
+use crate::{Negotiated, ProtocolChoiceError};
 
 /// Future, returned by `dialer_select_proto`, which selects a protocol and dialer
 /// either sequentially of by considering all protocols in parallel.
@@ -125,7 +125,7 @@ where
     I: Iterator,
     I::Item: AsRef<[u8]> + Clone
 {
-    type Item = (I::Item, R);
+    type Item = (I::Item, Negotiated<R>);
     type Error = ProtocolChoiceError;
 
     fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
@@ -207,7 +207,7 @@ where
                         ListenerToDialerMessage::ProtocolAck { ref name }
                             if name.as_ref() == proto_name.as_ref() =>
                         {
-                            return Ok(Async::Ready((proto_name, r.into_inner())))
+                            return Ok(Async::Ready((proto_name, Negotiated(r.into_inner()))))
                         }
                         ListenerToDialerMessage::NotAvailable => {
                             let proto_name = protocols.next()
@@ -300,7 +300,7 @@ where
     I: Iterator,
     I::Item: AsRef<[u8]> + Clone
 {
-    type Item = (I::Item, R);
+    type Item = (I::Item, Negotiated<R>);
     type Error = ProtocolChoiceError;
 
     fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
@@ -423,7 +423,7 @@ where
                         Some(ListenerToDialerMessage::ProtocolAck { ref name })
                             if name.as_ref() == proto_name.as_ref() =>
                         {
-                            return Ok(Async::Ready((proto_name, dialer.into_inner())))
+                            return Ok(Async::Ready((proto_name, Negotiated(dialer.into_inner()))))
                         }
                         _ => return Err(ProtocolChoiceError::UnexpectedMessage)
                     }
diff --git a/misc/multistream-select/src/lib.rs b/misc/multistream-select/src/lib.rs
index 984c4d17..7d50555d 100644
--- a/misc/multistream-select/src/lib.rs
+++ b/misc/multistream-select/src/lib.rs
@@ -74,6 +74,49 @@ mod tests;
 
 mod protocol;
 
+use futures::prelude::*;
+use std::io;
+
 pub use self::dialer_select::{dialer_select_proto, DialerSelectFuture};
 pub use self::error::ProtocolChoiceError;
 pub use self::listener_select::{listener_select_proto, ListenerSelectFuture};
+
+/// A stream after it has been negotiated.
+pub struct Negotiated<TInner>(pub(crate) TInner);
+
+impl<TInner> io::Read for Negotiated<TInner>
+where
+    TInner: io::Read
+{
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.0.read(buf)
+    }
+}
+
+impl<TInner> tokio_io::AsyncRead for Negotiated<TInner>
+where
+    TInner: tokio_io::AsyncRead
+{
+}
+
+impl<TInner> io::Write for Negotiated<TInner>
+where
+    TInner: io::Write
+{
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.0.write(buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.0.flush()
+    }
+}
+
+impl<TInner> tokio_io::AsyncWrite for Negotiated<TInner>
+where
+    TInner: tokio_io::AsyncWrite
+{
+    fn shutdown(&mut self) -> Poll<(), io::Error> {
+        self.0.shutdown()
+    }
+}
diff --git a/misc/multistream-select/src/listener_select.rs b/misc/multistream-select/src/listener_select.rs
index 261155ae..59492dc0 100644
--- a/misc/multistream-select/src/listener_select.rs
+++ b/misc/multistream-select/src/listener_select.rs
@@ -31,7 +31,7 @@ use crate::protocol::{
 use log::{debug, trace};
 use std::mem;
 use tokio_io::{AsyncRead, AsyncWrite};
-use crate::ProtocolChoiceError;
+use crate::{Negotiated, ProtocolChoiceError};
 
 /// Helps selecting a protocol amongst the ones supported.
 ///
@@ -99,7 +99,7 @@ where
     for<'a> &'a I: IntoIterator<Item = X>,
     X: AsRef<[u8]> + Clone
 {
-    type Item = (X, R, I);
+    type Item = (X, Negotiated<R>, I);
     type Error = ProtocolChoiceError;
 
     fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
@@ -171,7 +171,7 @@ where
                         }
                     };
                     if let Some(p) = outcome {
-                        return Ok(Async::Ready((p, listener.into_inner(), protocols)))
+                        return Ok(Async::Ready((p, Negotiated(listener.into_inner()), protocols)))
                     } else {
                         let stream = listener.into_future();
                         self.inner = ListenerSelectState::Incoming { stream, protocols }
diff --git a/muxers/mplex/src/lib.rs b/muxers/mplex/src/lib.rs
index 37306f52..d5f93e64 100644
--- a/muxers/mplex/src/lib.rs
+++ b/muxers/mplex/src/lib.rs
@@ -27,7 +27,7 @@ use bytes::Bytes;
 use libp2p_core::{
     Endpoint,
     StreamMuxer,
-    upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo}
+    upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo, Negotiated}
 };
 use log::{debug, trace};
 use parking_lot::Mutex;
@@ -158,11 +158,11 @@ impl<C> InboundUpgrade<C> for MplexConfig
 where
     C: AsyncRead + AsyncWrite,
 {
-    type Output = Multiplex<C>;
+    type Output = Multiplex<Negotiated<C>>;
     type Error = IoError;
     type Future = future::FutureResult<Self::Output, IoError>;
 
-    fn upgrade_inbound(self, socket: C, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, socket: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ok(self.upgrade(socket))
     }
 }
@@ -171,11 +171,11 @@ impl<C> OutboundUpgrade<C> for MplexConfig
 where
     C: AsyncRead + AsyncWrite,
 {
-    type Output = Multiplex<C>;
+    type Output = Multiplex<Negotiated<C>>;
     type Error = IoError;
     type Future = future::FutureResult<Self::Output, IoError>;
 
-    fn upgrade_outbound(self, socket: C, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, socket: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ok(self.upgrade(socket))
     }
 }
diff --git a/muxers/yamux/src/lib.rs b/muxers/yamux/src/lib.rs
index 97c8ca16..fbca83d9 100644
--- a/muxers/yamux/src/lib.rs
+++ b/muxers/yamux/src/lib.rs
@@ -22,7 +22,7 @@
 //! [specification](https://github.com/hashicorp/yamux/blob/master/spec.md).
 
 use futures::{future::{self, FutureResult}, prelude::*};
-use libp2p_core::upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo};
+use libp2p_core::upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo, Negotiated};
 use log::debug;
 use std::{io, iter, sync::atomic};
 use std::io::{Error as IoError};
@@ -155,11 +155,11 @@ impl<C> InboundUpgrade<C> for Config
 where
     C: AsyncRead + AsyncWrite + 'static,
 {
-    type Output = Yamux<C>;
+    type Output = Yamux<Negotiated<C>>;
     type Error = io::Error;
-    type Future = FutureResult<Yamux<C>, io::Error>;
+    type Future = FutureResult<Yamux<Negotiated<C>>, io::Error>;
 
-    fn upgrade_inbound(self, i: C, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, i: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ok(Yamux::new(i, self.0, yamux::Mode::Server))
     }
 }
@@ -168,11 +168,11 @@ impl<C> OutboundUpgrade<C> for Config
 where
     C: AsyncRead + AsyncWrite + 'static,
 {
-    type Output = Yamux<C>;
+    type Output = Yamux<Negotiated<C>>;
     type Error = io::Error;
-    type Future = FutureResult<Yamux<C>, io::Error>;
+    type Future = FutureResult<Yamux<Negotiated<C>>, io::Error>;
 
-    fn upgrade_outbound(self, i: C, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, i: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ok(Yamux::new(i, self.0, yamux::Mode::Client))
     }
 }
diff --git a/protocols/floodsub/src/protocol.rs b/protocols/floodsub/src/protocol.rs
index 5c72794b..532a0f88 100644
--- a/protocols/floodsub/src/protocol.rs
+++ b/protocols/floodsub/src/protocol.rs
@@ -53,10 +53,10 @@ where
 {
     type Output = FloodsubRpc;
     type Error = FloodsubDecodeError;
-    type Future = upgrade::ReadOneThen<TSocket, (), fn(Vec<u8>, ()) -> Result<FloodsubRpc, FloodsubDecodeError>>;
+    type Future = upgrade::ReadOneThen<upgrade::Negotiated<TSocket>, (), fn(Vec<u8>, ()) -> Result<FloodsubRpc, FloodsubDecodeError>>;
 
     #[inline]
-    fn upgrade_inbound(self, socket: TSocket, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, socket: upgrade::Negotiated<TSocket>, _: Self::Info) -> Self::Future {
         upgrade::read_one_then(socket, 2048, (), |packet, ()| {
             let mut rpc: rpc_proto::RPC = protobuf::parse_from_bytes(&packet)?;
 
@@ -168,10 +168,10 @@ where
 {
     type Output = ();
     type Error = io::Error;
-    type Future = upgrade::WriteOne<TSocket>;
+    type Future = upgrade::WriteOne<upgrade::Negotiated<TSocket>>;
 
     #[inline]
-    fn upgrade_outbound(self, socket: TSocket, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, socket: upgrade::Negotiated<TSocket>, _: Self::Info) -> Self::Future {
         let bytes = self.into_bytes();
         upgrade::write_one(socket, bytes)
     }
diff --git a/protocols/identify/src/identify.rs b/protocols/identify/src/identify.rs
index fdf2ea90..ece74624 100644
--- a/protocols/identify/src/identify.rs
+++ b/protocols/identify/src/identify.rs
@@ -24,7 +24,7 @@ use crate::protocol::{IdentifyInfo, IdentifySender, IdentifySenderFuture};
 use futures::prelude::*;
 use libp2p_core::protocols_handler::{ProtocolsHandler, ProtocolsHandlerSelect, ProtocolsHandlerUpgrErr};
 use libp2p_core::swarm::{ConnectedPoint, NetworkBehaviour, NetworkBehaviourAction, PollParameters};
-use libp2p_core::{Multiaddr, PeerId, PublicKey, either::EitherOutput};
+use libp2p_core::{Multiaddr, PeerId, PublicKey, either::EitherOutput, upgrade::Negotiated};
 use smallvec::SmallVec;
 use std::{collections::HashMap, collections::VecDeque, io};
 use tokio_io::{AsyncRead, AsyncWrite};
@@ -42,9 +42,9 @@ pub struct Identify<TSubstream> {
     /// For each peer we're connected to, the observed address to send back to it.
     observed_addresses: HashMap<PeerId, Multiaddr>,
     /// List of senders to answer, with the observed multiaddr.
-    to_answer: SmallVec<[(PeerId, IdentifySender<TSubstream>, Multiaddr); 4]>,
+    to_answer: SmallVec<[(PeerId, IdentifySender<Negotiated<TSubstream>>, Multiaddr); 4]>,
     /// List of futures that send back information back to remotes.
-    futures: SmallVec<[(PeerId, IdentifySenderFuture<TSubstream>); 4]>,
+    futures: SmallVec<[(PeerId, IdentifySenderFuture<Negotiated<TSubstream>>); 4]>,
     /// Events that need to be produced outside when polling..
     events: VecDeque<NetworkBehaviourAction<EitherOutput<Void, Void>, IdentifyEvent>>,
 }
diff --git a/protocols/identify/src/listen_handler.rs b/protocols/identify/src/listen_handler.rs
index eebaa793..ca57b101 100644
--- a/protocols/identify/src/listen_handler.rs
+++ b/protocols/identify/src/listen_handler.rs
@@ -22,7 +22,7 @@ use crate::protocol::{IdentifySender, IdentifyProtocolConfig};
 use futures::prelude::*;
 use libp2p_core::{
     protocols_handler::{KeepAlive, ProtocolsHandler, ProtocolsHandlerEvent, ProtocolsHandlerUpgrErr},
-    upgrade::{DeniedUpgrade, InboundUpgrade, OutboundUpgrade}
+    upgrade::{DeniedUpgrade, InboundUpgrade, OutboundUpgrade, Negotiated}
 };
 use smallvec::SmallVec;
 use tokio_io::{AsyncRead, AsyncWrite};
@@ -34,7 +34,7 @@ pub struct IdentifyListenHandler<TSubstream> {
     config: IdentifyProtocolConfig,
 
     /// List of senders to yield to the user.
-    pending_result: SmallVec<[IdentifySender<TSubstream>; 4]>,
+    pending_result: SmallVec<[IdentifySender<Negotiated<TSubstream>>; 4]>,
 }
 
 impl<TSubstream> IdentifyListenHandler<TSubstream> {
@@ -53,7 +53,7 @@ where
     TSubstream: AsyncRead + AsyncWrite,
 {
     type InEvent = Void;
-    type OutEvent = IdentifySender<TSubstream>;
+    type OutEvent = IdentifySender<Negotiated<TSubstream>>;
     type Error = Void;
     type Substream = TSubstream;
     type InboundProtocol = IdentifyProtocolConfig;
diff --git a/protocols/identify/src/protocol.rs b/protocols/identify/src/protocol.rs
index 22454a8c..27f84c4b 100644
--- a/protocols/identify/src/protocol.rs
+++ b/protocols/identify/src/protocol.rs
@@ -24,7 +24,7 @@ use futures::{future::{self, FutureResult}, Async, AsyncSink, Future, Poll, Sink
 use futures::try_ready;
 use libp2p_core::{
     Multiaddr, PublicKey,
-    upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo}
+    upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo, Negotiated}
 };
 use log::{debug, trace};
 use protobuf::Message as ProtobufMessage;
@@ -150,11 +150,11 @@ impl<C> InboundUpgrade<C> for IdentifyProtocolConfig
 where
     C: AsyncRead + AsyncWrite,
 {
-    type Output = IdentifySender<C>;
+    type Output = IdentifySender<Negotiated<C>>;
     type Error = IoError;
     type Future = FutureResult<Self::Output, IoError>;
 
-    fn upgrade_inbound(self, socket: C, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, socket: Negotiated<C>, _: Self::Info) -> Self::Future {
         trace!("Upgrading inbound connection");
         let socket = Framed::new(socket, codec::UviBytes::default());
         let sender = IdentifySender { inner: socket };
@@ -168,9 +168,9 @@ where
 {
     type Output = RemoteInfo;
     type Error = IoError;
-    type Future = IdentifyOutboundFuture<C>;
+    type Future = IdentifyOutboundFuture<Negotiated<C>>;
 
-    fn upgrade_outbound(self, socket: C, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, socket: Negotiated<C>, _: Self::Info) -> Self::Future {
         IdentifyOutboundFuture {
             inner: Framed::new(socket, codec::UviBytes::<BytesMut>::default()),
             shutdown: false,
diff --git a/protocols/kad/src/handler.rs b/protocols/kad/src/handler.rs
index 00f66a53..1d765830 100644
--- a/protocols/kad/src/handler.rs
+++ b/protocols/kad/src/handler.rs
@@ -24,7 +24,7 @@ use crate::protocol::{
 };
 use futures::prelude::*;
 use libp2p_core::protocols_handler::{KeepAlive, ProtocolsHandler, ProtocolsHandlerEvent, ProtocolsHandlerUpgrErr};
-use libp2p_core::{upgrade, either::EitherOutput, InboundUpgrade, OutboundUpgrade, PeerId};
+use libp2p_core::{upgrade, either::EitherOutput, InboundUpgrade, OutboundUpgrade, PeerId, upgrade::Negotiated};
 use multihash::Multihash;
 use std::{error, fmt, io, time::Duration, time::Instant};
 use tokio_io::{AsyncRead, AsyncWrite};
@@ -49,7 +49,7 @@ where
     next_connec_unique_id: UniqueConnecId,
 
     /// List of active substreams with the state they are in.
-    substreams: Vec<SubstreamState<TSubstream, TUserData>>,
+    substreams: Vec<SubstreamState<Negotiated<TSubstream>, TUserData>>,
 
     /// Until when to keep the connection alive.
     keep_alive: KeepAlive,
diff --git a/protocols/kad/src/protocol.rs b/protocols/kad/src/protocol.rs
index e401e3ef..5efc0fcb 100644
--- a/protocols/kad/src/protocol.rs
+++ b/protocols/kad/src/protocol.rs
@@ -29,7 +29,7 @@
 use bytes::BytesMut;
 use crate::protobuf_structs;
 use futures::{future, sink, stream, Sink, Stream};
-use libp2p_core::{InboundUpgrade, Multiaddr, OutboundUpgrade, PeerId, UpgradeInfo};
+use libp2p_core::{InboundUpgrade, Multiaddr, OutboundUpgrade, PeerId, UpgradeInfo, upgrade::Negotiated};
 use multihash::Multihash;
 use protobuf::{self, Message};
 use std::io::{Error as IoError, ErrorKind as IoErrorKind};
@@ -153,12 +153,12 @@ impl<C> InboundUpgrade<C> for KademliaProtocolConfig
 where
     C: AsyncRead + AsyncWrite,
 {
-    type Output = KadInStreamSink<C>;
+    type Output = KadInStreamSink<Negotiated<C>>;
     type Future = future::FutureResult<Self::Output, IoError>;
     type Error = IoError;
 
     #[inline]
-    fn upgrade_inbound(self, incoming: C, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, incoming: Negotiated<C>, _: Self::Info) -> Self::Future {
         let mut codec = codec::UviBytes::default();
         codec.set_max_len(4096);
 
@@ -182,12 +182,12 @@ impl<C> OutboundUpgrade<C> for KademliaProtocolConfig
 where
     C: AsyncRead + AsyncWrite,
 {
-    type Output = KadOutStreamSink<C>;
+    type Output = KadOutStreamSink<Negotiated<C>>;
     type Future = future::FutureResult<Self::Output, IoError>;
     type Error = IoError;
 
     #[inline]
-    fn upgrade_outbound(self, incoming: C, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, incoming: Negotiated<C>, _: Self::Info) -> Self::Future {
         let mut codec = codec::UviBytes::default();
         codec.set_max_len(4096);
 
diff --git a/protocols/noise/src/lib.rs b/protocols/noise/src/lib.rs
index 2bc68584..c4e34b31 100644
--- a/protocols/noise/src/lib.rs
+++ b/protocols/noise/src/lib.rs
@@ -58,7 +58,7 @@ pub use io::NoiseOutput;
 pub use protocol::{Keypair, PublicKey, Protocol, ProtocolParams, IX, IK, XX};
 pub use protocol::x25519::X25519;
 
-use libp2p_core::{UpgradeInfo, InboundUpgrade, OutboundUpgrade};
+use libp2p_core::{UpgradeInfo, InboundUpgrade, OutboundUpgrade, upgrade::Negotiated};
 use tokio_io::{AsyncRead, AsyncWrite};
 use zeroize::Zeroize;
 
@@ -127,11 +127,11 @@ where
     NoiseConfig<IX, C>: UpgradeInfo,
     C: Protocol<C> + AsRef<[u8]> + Zeroize
 {
-    type Output = (PublicKey<C>, NoiseOutput<T>);
+    type Output = (PublicKey<C>, NoiseOutput<Negotiated<T>>);
     type Error = NoiseError;
-    type Future = rt1::NoiseInboundFuture<T, C>;
+    type Future = rt1::NoiseInboundFuture<Negotiated<T>, C>;
 
-    fn upgrade_inbound(self, socket: T, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, socket: Negotiated<T>, _: Self::Info) -> Self::Future {
         let session = self.params.into_builder()
             .local_private_key(self.keys.secret().as_ref())
             .build_responder()
@@ -146,11 +146,11 @@ where
     NoiseConfig<IX, C>: UpgradeInfo,
     C: Protocol<C> + AsRef<[u8]> + Zeroize
 {
-    type Output = (PublicKey<C>, NoiseOutput<T>);
+    type Output = (PublicKey<C>, NoiseOutput<Negotiated<T>>);
     type Error = NoiseError;
-    type Future = rt1::NoiseOutboundFuture<T, C>;
+    type Future = rt1::NoiseOutboundFuture<Negotiated<T>, C>;
 
-    fn upgrade_outbound(self, socket: T, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, socket: Negotiated<T>, _: Self::Info) -> Self::Future {
         let session = self.params.into_builder()
             .local_private_key(self.keys.secret().as_ref())
             .build_initiator()
@@ -167,11 +167,11 @@ where
     NoiseConfig<XX, C>: UpgradeInfo,
     C: Protocol<C> + AsRef<[u8]> + Zeroize
 {
-    type Output = (PublicKey<C>, NoiseOutput<T>);
+    type Output = (PublicKey<C>, NoiseOutput<Negotiated<T>>);
     type Error = NoiseError;
-    type Future = rt15::NoiseInboundFuture<T, C>;
+    type Future = rt15::NoiseInboundFuture<Negotiated<T>, C>;
 
-    fn upgrade_inbound(self, socket: T, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, socket: Negotiated<T>, _: Self::Info) -> Self::Future {
         let session = self.params.into_builder()
             .local_private_key(self.keys.secret().as_ref())
             .build_responder()
@@ -186,11 +186,11 @@ where
     NoiseConfig<XX, C>: UpgradeInfo,
     C: Protocol<C> + AsRef<[u8]> + Zeroize
 {
-    type Output = (PublicKey<C>, NoiseOutput<T>);
+    type Output = (PublicKey<C>, NoiseOutput<Negotiated<T>>);
     type Error = NoiseError;
-    type Future = rt15::NoiseOutboundFuture<T, C>;
+    type Future = rt15::NoiseOutboundFuture<Negotiated<T>, C>;
 
-    fn upgrade_outbound(self, socket: T, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, socket: Negotiated<T>, _: Self::Info) -> Self::Future {
         let session = self.params.into_builder()
             .local_private_key(self.keys.secret().as_ref())
             .build_initiator()
@@ -207,11 +207,11 @@ where
     NoiseConfig<IK, C>: UpgradeInfo,
     C: Protocol<C> + AsRef<[u8]> + Zeroize
 {
-    type Output = (PublicKey<C>, NoiseOutput<T>);
+    type Output = (PublicKey<C>, NoiseOutput<Negotiated<T>>);
     type Error = NoiseError;
-    type Future = rt1::NoiseInboundFuture<T, C>;
+    type Future = rt1::NoiseInboundFuture<Negotiated<T>, C>;
 
-    fn upgrade_inbound(self, socket: T, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, socket: Negotiated<T>, _: Self::Info) -> Self::Future {
         let session = self.params.into_builder()
             .local_private_key(self.keys.secret().as_ref())
             .build_responder()
@@ -226,11 +226,11 @@ where
     NoiseConfig<IK, C, PublicKey<C>>: UpgradeInfo,
     C: Protocol<C> + AsRef<[u8]> + Zeroize
 {
-    type Output = (PublicKey<C>, NoiseOutput<T>);
+    type Output = (PublicKey<C>, NoiseOutput<Negotiated<T>>);
     type Error = NoiseError;
-    type Future = rt1::NoiseOutboundFuture<T, C>;
+    type Future = rt1::NoiseOutboundFuture<Negotiated<T>, C>;
 
-    fn upgrade_outbound(self, socket: T, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, socket: Negotiated<T>, _: Self::Info) -> Self::Future {
         let session = self.params.into_builder()
             .local_private_key(self.keys.secret().as_ref())
             .remote_public_key(self.remote.as_ref())
diff --git a/protocols/observed/src/lib.rs b/protocols/observed/src/lib.rs
index 86818a2e..227e958e 100644
--- a/protocols/observed/src/lib.rs
+++ b/protocols/observed/src/lib.rs
@@ -23,7 +23,7 @@
 
 use bytes::Bytes;
 use futures::{future, prelude::*};
-use libp2p_core::{Multiaddr, upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo}};
+use libp2p_core::{Multiaddr, upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo, Negotiated}};
 use std::{io, iter};
 use tokio_codec::{FramedRead, FramedWrite};
 use tokio_io::{AsyncRead, AsyncWrite};
@@ -51,11 +51,11 @@ impl<C> InboundUpgrade<C> for Observed
 where
     C: AsyncRead + AsyncWrite + Send + 'static
 {
-    type Output = Sender<C>;
+    type Output = Sender<Negotiated<C>>;
     type Error = io::Error;
     type Future = Box<dyn Future<Item=Self::Output, Error=Self::Error> + Send>;
 
-    fn upgrade_inbound(self, conn: C, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, conn: Negotiated<C>, _: Self::Info) -> Self::Future {
         let io = FramedWrite::new(conn, UviBytes::default());
         Box::new(future::ok(Sender { io }))
     }
@@ -69,10 +69,10 @@ where
     type Error = io::Error;
     type Future = Box<dyn Future<Item=Self::Output, Error=Self::Error> + Send>;
 
-    fn upgrade_outbound(self, conn: C, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, conn: Negotiated<C>, _: Self::Info) -> Self::Future {
         let io = FramedRead::new(conn, UviBytes::default());
         let future = io.into_future()
-            .map_err(|(e, _): (io::Error, FramedRead<C, UviBytes>)| e)
+            .map_err(|(e, _): (io::Error, FramedRead<Negotiated<C>, UviBytes>)| e)
             .and_then(move |(bytes, _)| {
                 if let Some(b) = bytes {
                     let ma = Multiaddr::from_bytes(b.to_vec())
@@ -100,7 +100,7 @@ impl<C: AsyncWrite> Sender<C> {
 
 #[cfg(test)]
 mod tests {
-    use libp2p_core::{Multiaddr, upgrade::{InboundUpgrade, OutboundUpgrade}};
+    use libp2p_core::{Multiaddr, upgrade::{apply_inbound, apply_outbound}};
     use tokio::runtime::current_thread;
     use tokio::net::{TcpListener, TcpStream};
     use super::*;
@@ -115,17 +115,19 @@ mod tests {
 
         let server = server.incoming()
             .into_future()
-            .map_err(|(e, _)| e.into())
+            .map_err(|_| panic!())
             .and_then(move |(conn, _)| {
-                Observed::new().upgrade_inbound(conn.unwrap(), b"/paritytech/observed-address/0.1.0")
+                apply_inbound(conn.unwrap(), Observed::new())
             })
+            .map_err(|_| panic!())
             .and_then(move |sender| sender.send_address(observed_addr1));
 
         let client = TcpStream::connect(&server_addr)
-            .map_err(|e| e.into())
+            .map_err(|_| panic!())
             .and_then(|conn| {
-                Observed::new().upgrade_outbound(conn, b"/paritytech/observed-address/0.1.0")
+                apply_outbound(conn, Observed::new())
             })
+            .map_err(|_| panic!())
             .map(move |addr| {
                 eprintln!("{} {}", addr, observed_addr2);
                 assert_eq!(addr, observed_addr2)
@@ -133,7 +135,7 @@ mod tests {
 
         current_thread::block_on_all(future::lazy(move || {
             current_thread::spawn(server.map_err(|e| panic!("server error: {}", e)).map(|_| ()));
-            client.map_err(|e| panic!("client error: {}", e))
+            client
         }))
         .unwrap();
     }
diff --git a/protocols/ping/src/protocol.rs b/protocols/ping/src/protocol.rs
index a3e7b8bf..bb820e51 100644
--- a/protocols/ping/src/protocol.rs
+++ b/protocols/ping/src/protocol.rs
@@ -19,7 +19,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 use futures::{prelude::*, future, try_ready};
-use libp2p_core::{InboundUpgrade, OutboundUpgrade, UpgradeInfo};
+use libp2p_core::{InboundUpgrade, OutboundUpgrade, UpgradeInfo, upgrade::Negotiated};
 use log::debug;
 use rand::{distributions::Standard, prelude::*, rngs::EntropyRng};
 use std::{io, iter, time::Duration, time::Instant};
@@ -53,10 +53,10 @@ where
 {
     type Output = ();
     type Error = io::Error;
-    type Future = future::Map<future::AndThen<future::AndThen<future::AndThen<tokio_io::io::ReadExact<TSocket, [u8; 32]>, tokio_io::io::WriteAll<TSocket, [u8; 32]>, fn((TSocket, [u8; 32])) -> tokio_io::io::WriteAll<TSocket, [u8; 32]>>, tokio_io::io::Flush<TSocket>, fn((TSocket, [u8; 32])) -> tokio_io::io::Flush<TSocket>>, tokio_io::io::Shutdown<TSocket>, fn(TSocket) -> tokio_io::io::Shutdown<TSocket>>, fn(TSocket) -> ()>;
+    type Future = future::Map<future::AndThen<future::AndThen<future::AndThen<tokio_io::io::ReadExact<Negotiated<TSocket>, [u8; 32]>, tokio_io::io::WriteAll<Negotiated<TSocket>, [u8; 32]>, fn((Negotiated<TSocket>, [u8; 32])) -> tokio_io::io::WriteAll<Negotiated<TSocket>, [u8; 32]>>, tokio_io::io::Flush<Negotiated<TSocket>>, fn((Negotiated<TSocket>, [u8; 32])) -> tokio_io::io::Flush<Negotiated<TSocket>>>, tokio_io::io::Shutdown<Negotiated<TSocket>>, fn(Negotiated<TSocket>) -> tokio_io::io::Shutdown<Negotiated<TSocket>>>, fn(Negotiated<TSocket>) -> ()>;
 
     #[inline]
-    fn upgrade_inbound(self, socket: TSocket, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, socket: Negotiated<TSocket>, _: Self::Info) -> Self::Future {
         tokio_io::io::read_exact(socket, [0; 32])
             .and_then::<fn(_) -> _, _>(|(socket, buffer)| tokio_io::io::write_all(socket, buffer))
             .and_then::<fn(_) -> _, _>(|(socket, _)| tokio_io::io::flush(socket))
@@ -71,10 +71,10 @@ where
 {
     type Output = Duration;
     type Error = io::Error;
-    type Future = PingDialer<TSocket>;
+    type Future = PingDialer<Negotiated<TSocket>>;
 
     #[inline]
-    fn upgrade_outbound(self, socket: TSocket, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, socket: Negotiated<TSocket>, _: Self::Info) -> Self::Future {
         let payload: [u8; 32] = EntropyRng::default().sample(Standard);
         debug!("Preparing for ping with payload {:?}", payload);
 
diff --git a/protocols/plaintext/src/lib.rs b/protocols/plaintext/src/lib.rs
index c3ece927..c8c6aafb 100644
--- a/protocols/plaintext/src/lib.rs
+++ b/protocols/plaintext/src/lib.rs
@@ -19,7 +19,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 use futures::future::{self, FutureResult};
-use libp2p_core::{InboundUpgrade, OutboundUpgrade, UpgradeInfo};
+use libp2p_core::{InboundUpgrade, OutboundUpgrade, UpgradeInfo, upgrade::Negotiated};
 use std::iter;
 use void::Void;
 
@@ -36,21 +36,21 @@ impl UpgradeInfo for PlainTextConfig {
 }
 
 impl<C> InboundUpgrade<C> for PlainTextConfig {
-    type Output = C;
+    type Output = Negotiated<C>;
     type Error = Void;
-    type Future = FutureResult<C, Self::Error>;
+    type Future = FutureResult<Negotiated<C>, Self::Error>;
 
-    fn upgrade_inbound(self, i: C, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, i: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ok(i)
     }
 }
 
 impl<C> OutboundUpgrade<C> for PlainTextConfig {
-    type Output = C;
+    type Output = Negotiated<C>;
     type Error = Void;
-    type Future = FutureResult<C, Self::Error>;
+    type Future = FutureResult<Negotiated<C>, Self::Error>;
 
-    fn upgrade_outbound(self, i: C, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, i: Negotiated<C>, _: Self::Info) -> Self::Future {
         future::ok(i)
     }
 }
diff --git a/protocols/secio/src/lib.rs b/protocols/secio/src/lib.rs
index 24c057a7..5bc6b161 100644
--- a/protocols/secio/src/lib.rs
+++ b/protocols/secio/src/lib.rs
@@ -84,7 +84,7 @@ pub use self::error::SecioError;
 use bytes::BytesMut;
 use futures::stream::MapErr as StreamMapErr;
 use futures::{Future, Poll, Sink, StartSend, Stream};
-use libp2p_core::{PublicKey, identity, upgrade::{UpgradeInfo, InboundUpgrade, OutboundUpgrade}};
+use libp2p_core::{PublicKey, identity, upgrade::{UpgradeInfo, InboundUpgrade, OutboundUpgrade, Negotiated}};
 use log::debug;
 use rw_stream_sink::RwStreamSink;
 use std::io::{Error as IoError, ErrorKind as IoErrorKind};
@@ -195,11 +195,11 @@ impl<T> InboundUpgrade<T> for SecioConfig
 where
     T: AsyncRead + AsyncWrite + Send + 'static
 {
-    type Output = SecioOutput<T>;
+    type Output = SecioOutput<Negotiated<T>>;
     type Error = SecioError;
     type Future = Box<dyn Future<Item = Self::Output, Error = Self::Error> + Send>;
 
-    fn upgrade_inbound(self, socket: T, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, socket: Negotiated<T>, _: Self::Info) -> Self::Future {
         Box::new(self.handshake(socket))
     }
 }
@@ -208,11 +208,11 @@ impl<T> OutboundUpgrade<T> for SecioConfig
 where
     T: AsyncRead + AsyncWrite + Send + 'static
 {
-    type Output = SecioOutput<T>;
+    type Output = SecioOutput<Negotiated<T>>;
     type Error = SecioError;
     type Future = Box<dyn Future<Item = Self::Output, Error = Self::Error> + Send>;
 
-    fn upgrade_outbound(self, socket: T, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, socket: Negotiated<T>, _: Self::Info) -> Self::Future {
         Box::new(self.handshake(socket))
     }
 }
diff --git a/src/simple.rs b/src/simple.rs
index bf5b8dab..2395fb37 100644
--- a/src/simple.rs
+++ b/src/simple.rs
@@ -18,7 +18,7 @@
 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-use crate::core::upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo};
+use crate::core::upgrade::{InboundUpgrade, OutboundUpgrade, UpgradeInfo, Negotiated};
 use bytes::Bytes;
 use futures::{future::FromErr, prelude::*};
 use std::{iter, io::Error as IoError, sync::Arc};
@@ -70,7 +70,7 @@ impl<F> UpgradeInfo for SimpleProtocol<F> {
 impl<C, F, O> InboundUpgrade<C> for SimpleProtocol<F>
 where
     C: AsyncRead + AsyncWrite,
-    F: Fn(C) -> O,
+    F: Fn(Negotiated<C>) -> O,
     O: IntoFuture<Error = IoError>
 {
     type Output = O::Item;
@@ -78,7 +78,7 @@ where
     type Future = FromErr<O::Future, IoError>;
 
     #[inline]
-    fn upgrade_inbound(self, socket: C, _: Self::Info) -> Self::Future {
+    fn upgrade_inbound(self, socket: Negotiated<C>, _: Self::Info) -> Self::Future {
         let upgrade = &self.upgrade;
         upgrade(socket).into_future().from_err()
     }
@@ -87,7 +87,7 @@ where
 impl<C, F, O> OutboundUpgrade<C> for SimpleProtocol<F>
 where
     C: AsyncRead + AsyncWrite,
-    F: Fn(C) -> O,
+    F: Fn(Negotiated<C>) -> O,
     O: IntoFuture<Error = IoError>
 {
     type Output = O::Item;
@@ -95,7 +95,7 @@ where
     type Future = FromErr<O::Future, IoError>;
 
     #[inline]
-    fn upgrade_outbound(self, socket: C, _: Self::Info) -> Self::Future {
+    fn upgrade_outbound(self, socket: Negotiated<C>, _: Self::Info) -> Self::Future {
         let upgrade = &self.upgrade;
         upgrade(socket).into_future().from_err()
     }