diff --git a/core/lib/src/data/data.rs b/core/lib/src/data/data.rs
index 00a5ff78..da0f9be6 100644
--- a/core/lib/src/data/data.rs
+++ b/core/lib/src/data/data.rs
@@ -2,7 +2,7 @@ use std::future::Future;
 use std::io;
 use std::path::Path;
 
-use tokio::io::{AsyncRead, AsyncWrite};
+use tokio::io::AsyncWrite;
 
 use super::data_stream::DataStream;
 
@@ -47,7 +47,7 @@ const PEEK_BYTES: usize = 512;
 pub struct Data {
     buffer: Vec<u8>,
     is_complete: bool,
-    stream: Box<dyn AsyncRead + Unpin + Send + Sync>,
+    stream: AsyncReadBody,
 }
 
 impl Data {
@@ -69,7 +69,7 @@ impl Data {
     /// ```
     pub fn open(mut self) -> DataStream {
         let buffer = std::mem::replace(&mut self.buffer, vec![]);
-        let stream = std::mem::replace(&mut self.stream, Box::new(&[][..]));
+        let stream = std::mem::replace(&mut self.stream, AsyncReadBody::empty());
         DataStream(buffer, stream)
     }
 
@@ -210,7 +210,7 @@ impl Data {
         };
 
         trace_!("Peek bytes: {}/{} bytes.", peek_buf.len(), PEEK_BYTES);
-        Data { buffer: peek_buf, stream: Box::new(stream), is_complete: eof }
+        Data { buffer: peek_buf, stream, is_complete: eof }
     }
 
     /// This creates a `data` object from a local data source `data`.
@@ -218,7 +218,7 @@ impl Data {
     pub(crate) fn local(data: Vec<u8>) -> Data {
         Data {
             buffer: data,
-            stream: Box::new(&[][..]),
+            stream: AsyncReadBody::empty(),
             is_complete: true,
         }
     }
diff --git a/core/lib/src/data/data_stream.rs b/core/lib/src/data/data_stream.rs
index 9e17da45..db4e782f 100644
--- a/core/lib/src/data/data_stream.rs
+++ b/core/lib/src/data/data_stream.rs
@@ -3,20 +3,18 @@ use std::task::{Context, Poll};
 
 use tokio::io::AsyncRead;
 
-// TODO.async: Consider storing the real type here instead of a Box to avoid
-// the dynamic dispatch
+use crate::ext::AsyncReadBody;
+
 /// Raw data stream of a request body.
 ///
 /// This stream can only be obtained by calling
 /// [`Data::open()`](crate::data::Data::open()). The stream contains all of the data
 /// in the body of the request. It exposes no methods directly. Instead, it must
 /// be used as an opaque [`Read`] structure.
-pub struct DataStream(pub(crate) Vec<u8>, pub(crate) Box<dyn AsyncRead + Unpin + Send>);
+pub struct DataStream(pub(crate) Vec<u8>, pub(crate) AsyncReadBody);
 
 // TODO.async: Consider implementing `AsyncBufRead`
 
-// TODO: Have a `BufRead` impl for `DataStream`. At the moment, this isn't
-// possible since Hyper's `HttpReader` doesn't implement `BufRead`.
 impl AsyncRead for DataStream {
     #[inline(always)]
     fn poll_read(mut self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut [u8]) -> Poll<Result<usize, std::io::Error>> {
diff --git a/core/lib/src/ext.rs b/core/lib/src/ext.rs
index bf5a6264..9e9368ef 100644
--- a/core/lib/src/ext.rs
+++ b/core/lib/src/ext.rs
@@ -14,14 +14,13 @@ pub struct IntoBytesStream<R> {
     buffer: Vec<u8>,
 }
 
-// TODO.async: Verify correctness of this implementation.
 impl<R> Stream for IntoBytesStream<R>
     where R: AsyncRead + Unpin
 {
     type Item = Result<Bytes, io::Error>;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>{
-        assert!(self.buffer.len() == self.buf_size);
+        debug_assert!(self.buffer.len() == self.buf_size);
 
         let Self { ref mut inner, ref mut buffer, buf_size } = *self;
 
@@ -43,7 +42,6 @@ pub trait AsyncReadExt: AsyncRead {
         IntoBytesStream { inner: self, buf_size, buffer: vec![0; buf_size] }
     }
 
-    // TODO.async: Verify correctness of this implementation.
     fn read_max<'a>(&'a mut self, mut buf: &'a mut [u8]) -> BoxFuture<'_, io::Result<usize>>
         where Self: Send + Unpin
     {
@@ -52,7 +50,7 @@ pub trait AsyncReadExt: AsyncRead {
             while !buf.is_empty() {
                 match self.read(buf).await {
                     Ok(0) => break,
-                    Ok(n) => { let tmp = buf; buf = &mut tmp[n..]; }
+                    Ok(n) => buf = &mut buf[n..],
                     Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
                     Err(e) => return Err(e),
                 }
@@ -76,6 +74,12 @@ enum AsyncReadBodyState {
     Done,
 }
 
+impl AsyncReadBody {
+    pub fn empty() -> Self {
+        Self { inner: hyper::Body::empty(), state: AsyncReadBodyState::Done }
+    }
+}
+
 impl From<hyper::Body> for AsyncReadBody {
     fn from(body: hyper::Body) -> Self {
         Self { inner: body, state: AsyncReadBodyState::Pending }