diff --git a/src/blockdata/script.rs b/src/blockdata/script.rs
index ec1ae8b..116c2bd 100644
--- a/src/blockdata/script.rs
+++ b/src/blockdata/script.rs
@@ -25,12 +25,12 @@
 //!
 
 use std::default::Default;
-use std::{error, fmt};
+use std::{error, fmt, io};
 
 #[cfg(feature = "serde")] use serde;
 
 use blockdata::opcodes;
-use consensus::{encode, Decodable, Encodable, ReadExt, WriteExt};
+use consensus::{encode, Decodable, Encodable, ReadExt};
 use bitcoin_hashes::{hash160, sha256, Hash};
 #[cfg(feature="bitcoinconsensus")] use bitcoinconsensus;
 #[cfg(feature="bitcoinconsensus")] use std::convert;
@@ -725,9 +725,12 @@ impl serde::Serialize for Script {
 }
 
 // Network serialization
-impl<S: WriteExt> Encodable<S> for Script {
+impl Encodable for Script {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        s: S,
+    ) -> Result<usize, encode::Error> {
         self.0.consensus_encode(s)
     }
 }
diff --git a/src/blockdata/transaction.rs b/src/blockdata/transaction.rs
index e7c4675..3d83d06 100644
--- a/src/blockdata/transaction.rs
+++ b/src/blockdata/transaction.rs
@@ -25,7 +25,7 @@
 
 use byteorder::{LittleEndian, WriteBytesExt};
 use std::default::Default;
-use std::fmt;
+use std::{fmt, io};
 #[cfg(feature="bitcoinconsensus")] use std::collections::HashMap;
 
 use bitcoin_hashes::{self, sha256d, Hash};
@@ -34,7 +34,7 @@ use bitcoin_hashes::hex::FromHex;
 use util::hash::BitcoinHash;
 #[cfg(feature="bitcoinconsensus")] use blockdata::script;
 use blockdata::script::Script;
-use consensus::{encode, serialize, Decodable, Encodable, ReadExt, WriteExt};
+use consensus::{encode, serialize, Decodable, Encodable, ReadExt};
 use VarInt;
 
 /// A reference to a transaction output
@@ -439,9 +439,12 @@ impl BitcoinHash for Transaction {
 
 impl_consensus_encoding!(TxOut, value, script_pubkey);
 
-impl<S: WriteExt> Encodable<S> for OutPoint {
-    fn consensus_encode(&self, s: &mut S) -> Result <usize, encode::Error> {
-        let len = self.txid.consensus_encode(s)?;
+impl Encodable for OutPoint {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
+        let len = self.txid.consensus_encode(&mut s)?;
         Ok(len + self.vout.consensus_encode(s)?)
     }
 }
@@ -454,11 +457,14 @@ impl<D: ReadExt> Decodable<D> for OutPoint {
     }
 }
 
-impl<S: WriteExt> Encodable<S> for TxIn {
-    fn consensus_encode(&self, s: &mut S) -> Result <usize, encode::Error> {
+impl Encodable for TxIn {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
         let mut len = 0;
-        len += self.previous_output.consensus_encode(s)?;
-        len += self.script_sig.consensus_encode(s)?;
+        len += self.previous_output.consensus_encode(&mut s)?;
+        len += self.script_sig.consensus_encode(&mut s)?;
         len += self.sequence.consensus_encode(s)?;
         Ok(len)
     }
@@ -474,10 +480,13 @@ impl<D: ReadExt> Decodable<D> for TxIn {
     }
 }
 
-impl<S: WriteExt> Encodable<S> for Transaction {
-    fn consensus_encode(&self, s: &mut S) -> Result <usize, encode::Error> {
+impl Encodable for Transaction {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
         let mut len = 0;
-        len += self.version.consensus_encode(s)?;
+        len += self.version.consensus_encode(&mut s)?;
         let mut have_witness = self.input.is_empty();
         for input in &self.input {
             if !input.witness.is_empty() {
@@ -486,15 +495,15 @@ impl<S: WriteExt> Encodable<S> for Transaction {
             }
         }
         if !have_witness {
-            len += self.input.consensus_encode(s)?;
-            len += self.output.consensus_encode(s)?;
+            len += self.input.consensus_encode(&mut s)?;
+            len += self.output.consensus_encode(&mut s)?;
         } else {
-            len += 0u8.consensus_encode(s)?;
-            len += 1u8.consensus_encode(s)?;
-            len += self.input.consensus_encode(s)?;
-            len += self.output.consensus_encode(s)?;
+            len += 0u8.consensus_encode(&mut s)?;
+            len += 1u8.consensus_encode(&mut s)?;
+            len += self.input.consensus_encode(&mut s)?;
+            len += self.output.consensus_encode(&mut s)?;
             for input in &self.input {
-                len += input.witness.consensus_encode(s)?;
+                len += input.witness.consensus_encode(&mut s)?;
             }
         }
         len += self.lock_time.consensus_encode(s)?;
diff --git a/src/consensus/encode.rs b/src/consensus/encode.rs
index 02cf6af..a1e8822 100644
--- a/src/consensus/encode.rs
+++ b/src/consensus/encode.rs
@@ -199,18 +199,14 @@ impl From<psbt::Error> for Error {
 }
 
 /// Encode an object into a vector
-pub fn serialize<T: ?Sized>(data: &T) -> Vec<u8>
-     where T: Encodable<Cursor<Vec<u8>>>,
-{
+pub fn serialize<T: Encodable + ?Sized>(data: &T) -> Vec<u8> {
     let mut encoder = Cursor::new(vec![]);
     data.consensus_encode(&mut encoder).unwrap();
     encoder.into_inner()
 }
 
 /// Encode an object into a hex-encoded string
-pub fn serialize_hex<T: ?Sized>(data: &T) -> String
-     where T: Encodable<Cursor<Vec<u8>>>
-{
+pub fn serialize_hex<T: Encodable + ?Sized>(data: &T) -> String {
     hex_encode(serialize(data))
 }
 
@@ -370,11 +366,11 @@ impl<R: Read> ReadExt for R {
 pub const MAX_VEC_SIZE: usize = 32 * 1024 * 1024;
 
 /// Data which can be encoded in a consensus-consistent way
-pub trait Encodable<S: WriteExt> {
+pub trait Encodable {
     /// Encode an object with a well-defined format, should only ever error if
-    /// the underlying WriteExt errors. Returns the number of bytes written on
+    /// the underlying `Write` errors. Returns the number of bytes written on
     /// success
-    fn consensus_encode(&self, e: &mut S) -> Result<usize, self::Error>;
+    fn consensus_encode<W: io::Write>(&self, e: W) -> Result<usize, Error>;
 }
 
 /// Data which can be encoded in a consensus-consistent way
@@ -399,9 +395,12 @@ macro_rules! impl_int_encodable{
             fn consensus_decode(d: &mut D) -> Result<$ty, self::Error> { d.$meth_dec().map($ty::from_le) }
         }
 
-        impl<S: WriteExt> Encodable<S> for $ty {
+        impl Encodable for $ty {
             #[inline]
-            fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
+            fn consensus_encode<S: WriteExt>(
+                &self,
+                mut s: S,
+            ) -> Result<usize, self::Error> {
                 s.$meth_enc(self.to_le())?;
                 Ok(mem::size_of::<$ty>())
             }
@@ -433,14 +432,29 @@ impl VarInt {
     }
 }
 
-impl<S: WriteExt> Encodable<S> for VarInt {
+impl Encodable for VarInt {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
+    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, Error> {
         match self.0 {
-            0...0xFC             => { (self.0 as u8).consensus_encode(s)?; Ok(1) }
-            0xFD...0xFFFF        => { s.emit_u8(0xFD)?; (self.0 as u16).consensus_encode(s)?; Ok(3) }
-            0x10000...0xFFFFFFFF => { s.emit_u8(0xFE)?; (self.0 as u32).consensus_encode(s)?; Ok(5) }
-            _                    => { s.emit_u8(0xFF)?; (self.0 as u64).consensus_encode(s)?; Ok(9) }
+            0...0xFC => {
+                (self.0 as u8).consensus_encode(s)?;
+                Ok(1)
+            },
+            0xFD...0xFFFF => {
+                s.emit_u8(0xFD)?;
+                (self.0 as u16).consensus_encode(s)?;
+                Ok(3)
+            },
+            0x10000...0xFFFFFFFF => {
+                s.emit_u8(0xFE)?;
+                (self.0 as u32).consensus_encode(s)?;
+                Ok(5)
+            },
+            _ => {
+                s.emit_u8(0xFF)?;
+                (self.0 as u64).consensus_encode(s)?;
+                Ok(9)
+            },
         }
     }
 }
@@ -481,9 +495,9 @@ impl<D: ReadExt> Decodable<D> for VarInt {
 
 
 // Booleans
-impl<S: WriteExt> Encodable<S> for bool {
+impl Encodable for bool {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
+    fn consensus_encode<S: WriteExt>(&self, mut s: S) -> Result<usize, Error> {
         s.emit_u8(if *self {1} else {0})?;
         Ok(1)
     }
@@ -495,11 +509,11 @@ impl<D: ReadExt> Decodable<D> for bool {
 }
 
 // Strings
-impl<S: WriteExt> Encodable<S> for String {
+impl Encodable for String {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
+    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, Error> {
         let b = self.as_bytes();
-        let vi_len = VarInt(b.len() as u64).consensus_encode(s)?;
+        let vi_len = VarInt(b.len() as u64).consensus_encode(&mut s)?;
         s.emit_slice(&b)?;
         Ok(vi_len + b.len())
     }
@@ -517,9 +531,12 @@ impl<D: ReadExt> Decodable<D> for String {
 // Arrays
 macro_rules! impl_array {
     ( $size:expr ) => (
-        impl<S: WriteExt> Encodable<S> for [u8; $size] {
+        impl Encodable for [u8; $size] {
             #[inline]
-            fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
+            fn consensus_encode<S: WriteExt>(
+                &self,
+                mut s: S,
+            ) -> Result<usize, Error> {
                 s.emit_slice(&self[..])?;
                 Ok(self.len())
             }
@@ -555,10 +572,10 @@ impl<D: ReadExt> Decodable<D> for [u16; 8] {
     }
 }
 
-impl<S: WriteExt> Encodable<S> for [u16; 8] {
+impl Encodable for [u16; 8] {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
-        for c in self.iter() { c.consensus_encode(s)?; }
+    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, Error> {
+        for c in self.iter() { c.consensus_encode(&mut s)?; }
         Ok(16)
     }
 }
@@ -566,13 +583,16 @@ impl<S: WriteExt> Encodable<S> for [u16; 8] {
 // Vectors
 macro_rules! impl_vec {
     ($type: ty) => {
-        impl<S: WriteExt> Encodable<S> for Vec<$type> {
+        impl Encodable for Vec<$type> {
             #[inline]
-            fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
+            fn consensus_encode<S: io::Write>(
+                &self,
+                mut s: S,
+            ) -> Result<usize, Error> {
                 let mut len = 0;
-                len += VarInt(self.len() as u64).consensus_encode(s)?;
+                len += VarInt(self.len() as u64).consensus_encode(&mut s)?;
                 for c in self.iter() {
-                    len += c.consensus_encode(s)?;
+                    len += c.consensus_encode(&mut s)?;
                 }
                 Ok(len)
             }
@@ -604,10 +624,10 @@ impl_vec!(Vec<u8>);
 impl_vec!((u32, Address));
 impl_vec!(u64);
 
-impl<S: WriteExt> Encodable<S> for Vec<u8> {
+impl Encodable for Vec<u8> {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
-        let vi_len = VarInt(self.len() as u64).consensus_encode(s)?;
+    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, Error> {
+        let vi_len = VarInt(self.len() as u64).consensus_encode(&mut s)?;
         s.emit_slice(&self)?;
         Ok(vi_len + self.len())
     }
@@ -628,10 +648,10 @@ impl<D: ReadExt> Decodable<D> for Vec<u8> {
     }
 }
 
-impl<S: WriteExt> Encodable<S> for Box<[u8]> {
+impl Encodable for Box<[u8]> {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
-        let vi_len = VarInt(self.len() as u64).consensus_encode(s)?;
+    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, Error> {
+        let vi_len = VarInt(self.len() as u64).consensus_encode(&mut s)?;
         s.emit_slice(&self)?;
         Ok(vi_len + self.len())
     }
@@ -660,11 +680,11 @@ fn sha2_checksum(data: &[u8]) -> [u8; 4] {
 }
 
 // Checked data
-impl<S: WriteExt> Encodable<S> for CheckedData {
+impl Encodable for CheckedData {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
-        (self.0.len() as u32).consensus_encode(s)?;
-        sha2_checksum(&self.0).consensus_encode(s)?;
+    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, Error> {
+        (self.0.len() as u32).consensus_encode(&mut s)?;
+        sha2_checksum(&self.0).consensus_encode(&mut s)?;
         s.emit_slice(&self.0)?;
         Ok(8 + self.0.len())
     }
@@ -699,13 +719,16 @@ impl<D: ReadExt> Decodable<D> for CheckedData {
 // Tuples
 macro_rules! tuple_encode {
     ($($x:ident),*) => (
-        impl <S: WriteExt, $($x: Encodable<S>),*> Encodable<S> for ($($x),*) {
+        impl <$($x: Encodable),*> Encodable for ($($x),*) {
             #[inline]
             #[allow(non_snake_case)]
-            fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
+            fn consensus_encode<S: io::Write>(
+                &self,
+                mut s: S,
+            ) -> Result<usize, self::Error> {
                 let &($(ref $x),*) = self;
                 let mut len = 0;
-                $(len += $x.consensus_encode(s)?;)*
+                $(len += $x.consensus_encode(&mut s)?;)*
                 Ok(len)
             }
         }
@@ -725,8 +748,8 @@ tuple_encode!(T0, T1, T2, T3);
 tuple_encode!(T0, T1, T2, T3, T4, T5);
 tuple_encode!(T0, T1, T2, T3, T4, T5, T6, T7);
 
-impl<S: WriteExt> Encodable<S> for sha256d::Hash {
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, self::Error> {
+impl Encodable for sha256d::Hash {
+    fn consensus_encode<S: io::Write>(&self, s: S) -> Result<usize, Error> {
         self.into_inner().consensus_encode(s)
     }
 }
diff --git a/src/internal_macros.rs b/src/internal_macros.rs
index 27cbb5a..30fe0bb 100644
--- a/src/internal_macros.rs
+++ b/src/internal_macros.rs
@@ -18,11 +18,14 @@
 
 macro_rules! impl_consensus_encoding {
     ($thing:ident, $($field:ident),+) => (
-        impl<S: ::consensus::WriteExt> ::consensus::Encodable<S> for $thing {
+        impl ::consensus::Encodable for $thing {
             #[inline]
-            fn consensus_encode(&self, s: &mut S) -> Result<usize, ::consensus::encode::Error> {
+            fn consensus_encode<S: ::std::io::Write>(
+                &self,
+                mut s: S,
+            ) -> Result<usize, ::consensus::encode::Error> {
                 let mut len = 0;
-                $(len += self.$field.consensus_encode(s)?;)+
+                $(len += self.$field.consensus_encode(&mut s)?;)+
                 Ok(len)
             }
         }
diff --git a/src/network/address.rs b/src/network/address.rs
index 142ae41..87a9156 100644
--- a/src/network/address.rs
+++ b/src/network/address.rs
@@ -22,7 +22,7 @@ use std::io;
 use std::fmt;
 use std::net::{SocketAddr, Ipv6Addr, SocketAddrV4, SocketAddrV6};
 
-use consensus::{encode, ReadExt, WriteExt};
+use consensus::{encode, ReadExt};
 use consensus::encode::{Decodable, Encodable};
 
 /// A message which can be sent on the Bitcoin network
@@ -72,13 +72,15 @@ fn addr_to_be(addr: [u16; 8]) -> [u16; 8] {
      addr[4].to_be(), addr[5].to_be(), addr[6].to_be(), addr[7].to_be()]
 }
 
-impl<S: WriteExt> Encodable<S> for Address {
+impl Encodable for Address {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
-        let mut len = 0;
-        len += self.services.consensus_encode(s)?;
-        len += addr_to_be(self.address).consensus_encode(s)?;
-        len += self.port.to_be().consensus_encode(s)?;
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
+        let len = self.services.consensus_encode(&mut s)?
+            + addr_to_be(self.address).consensus_encode(&mut s)?
+            + self.port.to_be().consensus_encode(s)?;
         Ok(len)
     }
 }
diff --git a/src/network/message.rs b/src/network/message.rs
index d8dcfd0..de00d78 100644
--- a/src/network/message.rs
+++ b/src/network/message.rs
@@ -19,7 +19,7 @@
 //! also defines (de)serialization routines for many primitives.
 //!
 
-use std::{iter, mem};
+use std::{io, iter, mem};
 use std::io::Cursor;
 
 use blockdata::block;
@@ -30,16 +30,19 @@ use network::message_blockdata;
 use network::message_filter;
 use consensus::encode::{Decodable, Encodable};
 use consensus::encode::{CheckedData, VarInt};
-use consensus::{encode, serialize, ReadExt, WriteExt};
+use consensus::{encode, serialize, ReadExt};
 use consensus::encode::MAX_VEC_SIZE;
 
 /// Serializer for command string
 #[derive(PartialEq, Eq, Clone, Debug)]
 pub struct CommandString(pub String);
 
-impl<S: WriteExt> Encodable<S> for CommandString {
+impl Encodable for CommandString {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        s: S,
+    ) -> Result<usize, encode::Error> {
         let &CommandString(ref inner_str) = self;
         let mut rawbytes = [0u8; 12];
         let strbytes = inner_str.as_bytes();
@@ -160,24 +163,31 @@ impl RawNetworkMessage {
 }
 
 struct HeaderSerializationWrapper<'a>(&'a Vec<block::BlockHeader>);
-impl <'a, S: WriteExt> Encodable<S> for HeaderSerializationWrapper<'a> {
+
+impl<'a> Encodable for HeaderSerializationWrapper<'a> {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
         let mut len = 0;
-        len += VarInt(self.0.len() as u64).consensus_encode(s)?;
+        len += VarInt(self.0.len() as u64).consensus_encode(&mut s)?;
         for header in self.0.iter() {
-            len += header.consensus_encode(s)?;
-            len += 0u8.consensus_encode(s)?;
+            len += header.consensus_encode(&mut s)?;
+            len += 0u8.consensus_encode(&mut s)?;
         }
         Ok(len)
     }
 }
 
-impl<S: WriteExt> Encodable<S> for RawNetworkMessage {
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
+impl Encodable for RawNetworkMessage {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
         let mut len = 0;
-        len += self.magic.consensus_encode(s)?;
-        len += CommandString(self.command()).consensus_encode(s)?;
+        len += self.magic.consensus_encode(&mut s)?;
+        len += CommandString(self.command()).consensus_encode(&mut s)?;
         len += CheckedData(match self.payload {
             NetworkMessage::Version(ref dat) => serialize(dat),
             NetworkMessage::Addr(ref dat)    => serialize(dat),
@@ -202,7 +212,7 @@ impl<S: WriteExt> Encodable<S> for RawNetworkMessage {
             | NetworkMessage::SendHeaders
             | NetworkMessage::MemPool
             | NetworkMessage::GetAddr => vec![],
-        }).consensus_encode(s)?;
+        }).consensus_encode(&mut s)?;
         Ok(len)
     }
 }
diff --git a/src/network/message_blockdata.rs b/src/network/message_blockdata.rs
index c74c054..7d3a770 100644
--- a/src/network/message_blockdata.rs
+++ b/src/network/message_blockdata.rs
@@ -20,9 +20,11 @@
 
 use network::constants;
 use consensus::encode::{Decodable, Encodable};
-use consensus::{encode, ReadExt, WriteExt};
+use consensus::{encode, ReadExt};
 use bitcoin_hashes::sha256d;
 
+use std::io;
+
 #[derive(PartialEq, Eq, Clone, Debug)]
 /// The type of an inventory object
 pub enum InvType {
@@ -101,17 +103,20 @@ impl GetHeadersMessage {
 
 impl_consensus_encoding!(GetHeadersMessage, version, locator_hashes, stop_hash);
 
-impl<S: WriteExt> Encodable<S> for Inventory {
+impl Encodable for Inventory {
     #[inline]
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
         let inv_len = match self.inv_type {
-            InvType::Error => 0u32, 
+            InvType::Error => 0u32,
             InvType::Transaction => 1,
             InvType::Block => 2,
             InvType::WitnessBlock => 0x40000002,
             InvType::WitnessTransaction => 0x40000001
-        }.consensus_encode(s)?;
-        Ok(inv_len + self.hash.consensus_encode(s)?)
+        }.consensus_encode(&mut s)?;
+        Ok(inv_len + self.hash.consensus_encode(&mut s)?)
     }
 }
 
diff --git a/src/util/merkleblock.rs b/src/util/merkleblock.rs
index 9eb551e..bd42d60 100644
--- a/src/util/merkleblock.rs
+++ b/src/util/merkleblock.rs
@@ -57,12 +57,13 @@
 //! ```
 
 use std::collections::HashSet;
+use std::io;
 
 use bitcoin_hashes::{sha256d, Hash};
 
 use blockdata::constants::{MAX_BLOCK_WEIGHT, MIN_TRANSACTION_WEIGHT};
 use consensus::encode::{Encodable, Error};
-use consensus::{Decodable, ReadExt, WriteExt};
+use consensus::{Decodable, ReadExt};
 use util::hash::BitcoinHash;
 use util::merkleblock::MerkleBlockError::*;
 use {Block, BlockHeader};
@@ -353,10 +354,10 @@ impl PartialMerkleTree {
     }
 }
 
-impl<S: WriteExt> Encodable<S> for PartialMerkleTree {
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, Error> {
-        let ret = self.num_transactions.consensus_encode(s)?
-            + self.hashes.consensus_encode(s)?;
+impl Encodable for PartialMerkleTree {
+    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, Error> {
+        let ret = self.num_transactions.consensus_encode(&mut s)?
+            + self.hashes.consensus_encode(&mut s)?;
         let mut bytes: Vec<u8> = vec![0; (self.bits.len() + 7) / 8];
         for p in 0..self.bits.len() {
             bytes[p / 8] |= (self.bits[p] as u8) << (p % 8) as u8;
@@ -471,9 +472,11 @@ impl MerkleBlock {
     }
 }
 
-impl<S: WriteExt> Encodable<S> for MerkleBlock {
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, Error> {
-        Ok(self.header.consensus_encode(s)? + self.txn.consensus_encode(s)?)
+impl Encodable for MerkleBlock {
+    fn consensus_encode<S: io::Write>(&self, mut s: S) -> Result<usize, Error> {
+        let len = self.header.consensus_encode(&mut s)?
+            + self.txn.consensus_encode(s)?;
+        Ok(len)
     }
 }
 
diff --git a/src/util/psbt/macros.rs b/src/util/psbt/macros.rs
index 5e652c5..3531da6 100644
--- a/src/util/psbt/macros.rs
+++ b/src/util/psbt/macros.rs
@@ -54,11 +54,17 @@ macro_rules! impl_psbt_serialize {
 
 macro_rules! impl_psbtmap_consensus_encoding {
     ($thing:ty) => {
-        impl<S: ::consensus::WriteExt> ::consensus::Encodable<S> for $thing {
-            fn consensus_encode(&self, s: &mut S) -> Result<usize, ::consensus::encode::Error> {
+        impl ::consensus::Encodable for $thing {
+            fn consensus_encode<S: ::std::io::Write>(
+                &self,
+                mut s: S,
+            ) -> Result<usize, ::consensus::encode::Error> {
                 let mut len = 0;
                 for pair in ::util::psbt::Map::get_pairs(self)? {
-                    len += ::consensus::Encodable::consensus_encode(&pair, s)?;
+                    len += ::consensus::Encodable::consensus_encode(
+                        &pair,
+                        &mut s,
+                    )?;
                 }
 
                 Ok(len + ::consensus::Encodable::consensus_encode(&0x00_u8, s)?)
diff --git a/src/util/psbt/mod.rs b/src/util/psbt/mod.rs
index 088192b..342265c 100644
--- a/src/util/psbt/mod.rs
+++ b/src/util/psbt/mod.rs
@@ -20,7 +20,9 @@
 
 use blockdata::script::Script;
 use blockdata::transaction::Transaction;
-use consensus::{encode, Encodable, Decodable, WriteExt, ReadExt};
+use consensus::{encode, Encodable, Decodable, ReadExt};
+
+use std::io;
 
 mod error;
 pub use self::error::Error;
@@ -88,21 +90,24 @@ impl PartiallySignedTransaction {
     }
 }
 
-impl<S: WriteExt> Encodable<S> for PartiallySignedTransaction {
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
+impl Encodable for PartiallySignedTransaction {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
         let mut len = 0;
-        len += b"psbt".consensus_encode(s)?;
+        len += b"psbt".consensus_encode(&mut s)?;
 
-        len += 0xff_u8.consensus_encode(s)?;
+        len += 0xff_u8.consensus_encode(&mut s)?;
 
-        len += self.global.consensus_encode(s)?;
+        len += self.global.consensus_encode(&mut s)?;
 
         for i in &self.inputs {
-            len += i.consensus_encode(s)?;
+            len += i.consensus_encode(&mut s)?;
         }
 
         for i in &self.outputs {
-            len += i.consensus_encode(s)?;
+            len += i.consensus_encode(&mut s)?;
         }
 
         Ok(len)
diff --git a/src/util/psbt/raw.rs b/src/util/psbt/raw.rs
index 880b437..808f23b 100644
--- a/src/util/psbt/raw.rs
+++ b/src/util/psbt/raw.rs
@@ -17,10 +17,10 @@
 //! Raw PSBT key-value pairs as defined at
 //! https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki.
 
-use std::fmt;
+use std::{fmt, io};
 
 use consensus::encode::{Decodable, Encodable, VarInt, MAX_VEC_SIZE};
-use consensus::{encode, ReadExt, WriteExt};
+use consensus::{encode, ReadExt};
 use util::psbt::Error;
 
 /// A PSBT key in its raw byte form.
@@ -80,24 +80,30 @@ impl<D: ReadExt> Decodable<D> for Key {
     }
 }
 
-impl<S: WriteExt> Encodable<S> for Key {
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
+impl Encodable for Key {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
         let mut len = 0;
-        len += VarInt((self.key.len() + 1) as u64).consensus_encode(s)?;
+        len += VarInt((self.key.len() + 1) as u64).consensus_encode(&mut s)?;
 
-        len += self.type_value.consensus_encode(s)?;
+        len += self.type_value.consensus_encode(&mut s)?;
 
         for key in &self.key {
-            len += key.consensus_encode(s)?
+            len += key.consensus_encode(&mut s)?
         }
 
         Ok(len)
     }
 }
 
-impl<S: WriteExt> Encodable<S> for Pair {
-    fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
-        let len = self.key.consensus_encode(s)?;
+impl Encodable for Pair {
+    fn consensus_encode<S: io::Write>(
+        &self,
+        mut s: S,
+    ) -> Result<usize, encode::Error> {
+        let len = self.key.consensus_encode(&mut s)?;
         Ok(len + self.value.consensus_encode(s)?)
     }
 }
diff --git a/src/util/uint.rs b/src/util/uint.rs
index de98411..b1856a9 100644
--- a/src/util/uint.rs
+++ b/src/util/uint.rs
@@ -336,13 +336,16 @@ macro_rules! construct_uint {
             }
         }
 
-        impl<S: ::consensus::WriteExt> ::consensus::Encodable<S> for $name {
+        impl ::consensus::Encodable for $name {
             #[inline]
-            fn consensus_encode(&self, s: &mut S) -> Result<usize, encode::Error> {
+            fn consensus_encode<S: ::std::io::Write>(
+                &self,
+                mut s: S,
+            ) -> Result<usize, encode::Error> {
                 let &$name(ref data) = self;
                 let mut len = 0;
                 for word in data.iter() {
-                    len += word.consensus_encode(s)?;
+                    len += word.consensus_encode(&mut s)?;
                 }
                 Ok(len)
             }