diff --git a/src/http/body.rs b/src/http/body.rs
index 4f50471..7e3ea39 100644
--- a/src/http/body.rs
+++ b/src/http/body.rs
@@ -1,8 +1,35 @@
 //! HTTP body types
 
-use crate::io::{AsyncRead, Cursor, Empty};
+use crate::io::{AsyncInputStream, AsyncRead, Cursor, Empty};
+use core::fmt;
+use wasi::http::types::IncomingBody as WasiIncomingBody;
 
-pub use super::response::IncomingBody;
+pub use super::{
+    error::{Error, ErrorVariant},
+    HeaderMap,
+};
+
+#[derive(Debug)]
+pub(crate) enum BodyKind {
+    Fixed(u64),
+    Chunked,
+}
+
+impl BodyKind {
+    pub(crate) fn from_headers(headers: &HeaderMap) -> Result<BodyKind, InvalidContentLength> {
+        if let Some(value) = headers.get("content-length") {
+            let content_length = std::str::from_utf8(value.as_ref())
+                .unwrap()
+                .parse::<u64>()
+                .map_err(|_| InvalidContentLength)?;
+            Ok(BodyKind::Fixed(content_length))
+        } else if headers.contains_key("transfer-encoding") {
+            Ok(BodyKind::Chunked)
+        } else {
+            Ok(BodyKind::Chunked)
+        }
+    }
+}
 
 /// A trait representing an HTTP body.
 #[doc(hidden)]
@@ -82,3 +109,66 @@ impl Body for Empty {
         Some(0)
     }
 }
+
+/// An incoming HTTP body
+#[derive(Debug)]
+pub struct IncomingBody {
+    kind: BodyKind,
+    // IMPORTANT: the order of these fields here matters. `body_stream` must
+    // be dropped before `_incoming_body`.
+    body_stream: AsyncInputStream,
+    _incoming_body: WasiIncomingBody,
+}
+
+impl IncomingBody {
+    pub(crate) fn new(
+        kind: BodyKind,
+        body_stream: AsyncInputStream,
+        incoming_body: WasiIncomingBody,
+    ) -> Self {
+        Self {
+            kind,
+            body_stream,
+            _incoming_body: incoming_body,
+        }
+    }
+}
+
+impl AsyncRead for IncomingBody {
+    async fn read(&mut self, out_buf: &mut [u8]) -> crate::io::Result<usize> {
+        self.body_stream.read(out_buf).await
+    }
+}
+
+impl Body for IncomingBody {
+    fn len(&self) -> Option<usize> {
+        match self.kind {
+            BodyKind::Fixed(l) => {
+                if l > (usize::MAX as u64) {
+                    None
+                } else {
+                    Some(l as usize)
+                }
+            }
+            BodyKind::Chunked => None,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct InvalidContentLength;
+
+impl fmt::Display for InvalidContentLength {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        "incoming content-length should be a u64; violates HTTP/1.1".fmt(f)
+    }
+}
+
+impl std::error::Error for InvalidContentLength {}
+
+impl From<InvalidContentLength> for Error {
+    fn from(e: InvalidContentLength) -> Self {
+        // TODO: What's the right error code here?
+        ErrorVariant::Other(e.to_string()).into()
+    }
+}
diff --git a/src/http/response.rs b/src/http/response.rs
index 681b3bc..1544f8b 100644
--- a/src/http/response.rs
+++ b/src/http/response.rs
@@ -1,35 +1,15 @@
-use wasi::http::types::{IncomingBody as WasiIncomingBody, IncomingResponse};
-
-use super::{fields::header_map_from_wasi, Body, Error, HeaderMap, Result};
-use crate::io::{AsyncInputStream, AsyncRead};
+use wasi::http::types::IncomingResponse;
+
+use super::{
+    body::{BodyKind, IncomingBody},
+    fields::header_map_from_wasi,
+    Error, HeaderMap, Result,
+};
+use crate::io::AsyncInputStream;
 use http::StatusCode;
 
 pub use http::Response;
 
-#[derive(Debug)]
-enum BodyKind {
-    Fixed(u64),
-    Chunked,
-}
-
-impl BodyKind {
-    fn from_headers(headers: &HeaderMap) -> Result<BodyKind> {
-        if let Some(value) = headers.get("content-length") {
-            let content_length = std::str::from_utf8(value.as_ref())
-                .unwrap()
-                .parse::<u64>()
-                .map_err(|_| {
-                    Error::other("incoming content-length should be a u64; violates HTTP/1.1")
-                })?;
-            Ok(BodyKind::Fixed(content_length))
-        } else if headers.contains_key("transfer-encoding") {
-            Ok(BodyKind::Chunked)
-        } else {
-            Ok(BodyKind::Chunked)
-        }
-    }
-}
-
 pub(crate) fn try_from_incoming_response(
     incoming: IncomingResponse,
 ) -> Result<Response<IncomingBody>> {
@@ -48,11 +28,7 @@ pub(crate) fn try_from_incoming_response(
         .stream()
         .expect("cannot call `stream` twice on an incoming body");
 
-    let body = IncomingBody {
-        kind,
-        body_stream: AsyncInputStream::new(body_stream),
-        _incoming_body: incoming_body,
-    };
+    let body = IncomingBody::new(kind, AsyncInputStream::new(body_stream), incoming_body);
 
     let mut builder = Response::builder().status(status);
 
@@ -64,34 +40,3 @@ pub(crate) fn try_from_incoming_response(
         .body(body)
         .map_err(|err| Error::other(err.to_string()))
 }
-
-/// An incoming HTTP body
-#[derive(Debug)]
-pub struct IncomingBody {
-    kind: BodyKind,
-    // IMPORTANT: the order of these fields here matters. `body_stream` must
-    // be dropped before `_incoming_body`.
-    body_stream: AsyncInputStream,
-    _incoming_body: WasiIncomingBody,
-}
-
-impl AsyncRead for IncomingBody {
-    async fn read(&mut self, out_buf: &mut [u8]) -> crate::io::Result<usize> {
-        self.body_stream.read(out_buf).await
-    }
-}
-
-impl Body for IncomingBody {
-    fn len(&self) -> Option<usize> {
-        match self.kind {
-            BodyKind::Fixed(l) => {
-                if l > (usize::MAX as u64) {
-                    None
-                } else {
-                    Some(l as usize)
-                }
-            }
-            BodyKind::Chunked => None,
-        }
-    }
-}