diff --git a/src/conn.rs b/src/conn.rs
index c1d194b..4501361 100644
--- a/src/conn.rs
+++ b/src/conn.rs
@@ -22,6 +22,12 @@ impl ConnectionPool {
     ) -> Result<Response, Error> {
         //
 
+        let do_chunk = request.header("transfer-encoding")
+            // if the user has set an encoding header, obey that.
+            .map(|enc| enc.len() > 0)
+            // otherwise, no chunking.
+            .unwrap_or(false);
+
         let hostname = url.host_str().unwrap_or("localhost"); // is localhost a good alternative?
         let is_secure = url.scheme().eq_ignore_ascii_case("https");
 
@@ -31,13 +37,23 @@ impl ConnectionPool {
                 Some(jar) => match_cookies(jar, hostname, url.path(), is_secure),
             }
         };
-        let headers = request.headers.iter().chain(cookie_headers.iter());
+        let extra_headers = {
+            let mut extra = vec![];
 
-        let do_chunk = request.header("transfer-encoding")
-            // if the user has set an encoding header, obey that.
-            .map(|enc| enc.len() > 0)
-            // otherwise, no chunking.
-            .unwrap_or(false);
+            // chunking and Content-Length headers are mutually exclusive
+            // also don't write this if the user has set it themselves
+            if !do_chunk && !request.has("content-length") {
+                if let Some(size) = body.size {
+                    extra.push(format!("Content-Length: {}\r\n", size).parse::<Header>()?);
+                }
+            }
+            extra
+        };
+        let headers = request
+            .headers
+            .iter()
+            .chain(cookie_headers.iter())
+            .chain(extra_headers.iter());
 
         // open socket
         let mut stream = match url.scheme() {
@@ -56,13 +72,6 @@ impl ConnectionPool {
         for header in headers {
             write!(prelude, "{}: {}\r\n", header.name(), header.value())?;
         }
-        // chunking and Content-Length headers are mutually exclusive
-        // also don't write this if the user has set it themselves
-        if !do_chunk && !request.has("content-length") {
-            if let Some(size) = body.size {
-                write!(prelude, "Content-Length: {}\r\n", size)?;
-            }
-        }
         write!(prelude, "\r\n")?;
 
         stream.write_all(&mut prelude[..])?;
diff --git a/src/lib.rs b/src/lib.rs
index ac5f983..b4e8a2b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -41,8 +41,8 @@
 //!
 //! ```
 //! let resp = ureq::post("http://my-server.com/ingest")
-//!     .set("Transfer-Encoding", "chunked")`
-//!     .send("Hello world");
+//!     .set("Transfer-Encoding", "chunked")
+//!     .send_str("Hello world");
 //! ```
 
 extern crate ascii;
diff --git a/src/request.rs b/src/request.rs
index 434f015..e46a232 100644
--- a/src/request.rs
+++ b/src/request.rs
@@ -35,6 +35,16 @@ pub struct Request {
     redirects: u32,
 }
 
+impl ::std::fmt::Debug for Request {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::result::Result<(), ::std::fmt::Error> {
+        write!(
+            f,
+            "Request[{} {}, {}, {:?}]",
+            self.method, self.path, self.query, self.headers
+        )
+    }
+}
+
 enum Payload {
     Empty,
     Text(String),
diff --git a/src/test/body_send.rs b/src/test/body_send.rs
new file mode 100644
index 0000000..62191ad
--- /dev/null
+++ b/src/test/body_send.rs
@@ -0,0 +1,29 @@
+use test;
+
+use super::super::*;
+
+#[test]
+fn content_length_on_str() {
+    test::set_handler("/content_length_on_str", |_req, _url| {
+        test::make_response(200, "OK", vec![], vec![])
+    });
+    let resp = get("test://host/content_length_on_str")
+        .send_str("Hello World!!!");
+    let vec = resp.to_write_vec();
+    let s = String::from_utf8_lossy(&vec);
+    assert!(s.contains("\r\nContent-Length: 14\r\n"))
+}
+
+#[test]
+fn content_length_on_json() {
+    test::set_handler("/content_length_on_json", |_req, _url| {
+        test::make_response(200, "OK", vec![], vec![])
+    });
+    let mut json = SerdeMap::new();
+    json.insert("Hello".to_string(), SerdeValue::String("World!!!".to_string()));
+    let resp = get("test://host/content_length_on_json")
+        .send_json(SerdeValue::Object(json));
+    let vec = resp.to_write_vec();
+    let s = String::from_utf8_lossy(&vec);
+    assert!(s.contains("\r\nContent-Length: 20\r\n"))
+}
diff --git a/src/test/mod.rs b/src/test/mod.rs
index d38a759..2acd586 100644
--- a/src/test/mod.rs
+++ b/src/test/mod.rs
@@ -11,6 +11,7 @@ use std::io::Cursor;
 mod agent_test;
 mod auth;
 mod body_read;
+mod body_send;
 mod simple;
 
 type RequestHandler = Fn(&Request, &Url) -> Result<Stream, Error> + Send + 'static;