diff --git a/src/async_impl/body.rs b/src/async_impl/body.rs
index e081e0d796..419d00e5c3 100644
--- a/src/async_impl/body.rs
+++ b/src/async_impl/body.rs
@@ -354,6 +354,8 @@ where
 
 #[cfg(test)]
 mod tests {
+    use http_body::Body as _;
+
     use super::Body;
 
     #[test]
@@ -362,4 +364,11 @@ mod tests {
         let body = Body::from(&test_data[..]);
         assert_eq!(body.as_bytes(), Some(&test_data[..]));
     }
+
+    #[test]
+    fn body_exact_length() {
+        assert_eq!(Body::empty().size_hint().exact(), None);
+        assert_eq!(Body::reusable("abc".into()).size_hint().exact(), Some(3));
+        assert_eq!(Body::streaming(Body::reusable("abc".into())).size_hint().exact(), None);
+    }
 }
diff --git a/tests/blocking.rs b/tests/blocking.rs
index c4ea04befe..62370a0f18 100644
--- a/tests/blocking.rs
+++ b/tests/blocking.rs
@@ -21,6 +21,27 @@ fn test_response_text() {
     assert_eq!(b"Hello", body.as_bytes());
 }
 
+#[test]
+fn donot_set_conent_length_0_if_have_no_body() {
+    let server = server::http(move |req| async move {
+        let headers = req.headers();
+        assert_eq!(headers.get("content-length"), None);
+        dbg!(&headers);
+        http::Response::default()
+    });
+
+    let url = format!("http://{}/conent-length", server.addr());
+    let res = reqwest::blocking::Client::builder()
+        .no_proxy()
+        .build()
+        .expect("client builder")
+        .get(&url)
+        .send()
+        .expect("request");
+
+    assert_eq!(res.status(), reqwest::StatusCode::OK);
+}
+
 #[test]
 #[cfg(feature = "charset")]
 fn test_response_non_utf_8_text() {
diff --git a/tests/client.rs b/tests/client.rs
index 02f32fc854..60eea57e0d 100644
--- a/tests/client.rs
+++ b/tests/client.rs
@@ -54,6 +54,28 @@ async fn auto_headers() {
     assert_eq!(res.remote_addr(), Some(server.addr()));
 }
 
+#[tokio::test]
+async fn donot_set_conent_length_0_if_have_no_body() {
+    let server = server::http(move |req| async move {
+        let headers = req.headers();
+        assert_eq!(headers.get("content-length"), None);
+        dbg!(&headers);
+        http::Response::default()
+    });
+
+    let url = format!("http://{}/conent-length", server.addr());
+    let res = reqwest::Client::builder()
+        .no_proxy()
+        .build()
+        .expect("client builder")
+        .get(&url)
+        .send()
+        .await
+        .expect("request");
+
+    assert_eq!(res.status(), reqwest::StatusCode::OK);
+}
+
 #[tokio::test]
 async fn user_agent() {
     let server = server::http(move |req| async move {