diff --git a/src/handshake/client.rs b/src/handshake/client.rs
index cd5e6d0..d6a5264 100644
--- a/src/handshake/client.rs
+++ b/src/handshake/client.rs
@@ -1,5 +1,6 @@
 //! Client handshake machine.
 
+use std::borrow::Cow;
 use std::io::{Read, Write};
 use std::marker::PhantomData;
 
@@ -20,11 +21,11 @@ pub struct Request<'t> {
     /// `ws://` or `wss://` URL to connect to.
     pub url: Url,
     /// Extra HTTP headers to append to the request.
-    pub extra_headers: Option<&'t [(&'t str, &'t str)]>,
+    pub extra_headers: Option<Vec<(Cow<'t, str>, Cow<'t, str>)>>,
 }
 
 impl<'t> Request<'t> {
-    /// The GET part of the request.
+    /// Returns the GET part of the request.
     fn get_path(&self) -> String {
         if let Some(query) = self.url.query() {
             format!("{path}?{query}", path = self.url.path(), query = query)
@@ -32,7 +33,8 @@ impl<'t> Request<'t> {
             self.url.path().into()
         }
     }
-    /// The Host: part of the request.
+
+    /// Returns the host part of the request.
     fn get_host(&self) -> String {
         let host = self.url.host_str().expect("Bug: URL without host");
         if let Some(port) = self.url.port() {
@@ -41,6 +43,18 @@ impl<'t> Request<'t> {
             host.into()
         }
     }
+
+    /// Adds a WebSocket protocol to the request.
+    pub fn add_protocol(&mut self, protocol: Cow<'t, str>) {
+        self.add_header(Cow::from("Sec-WebSocket-Protocol"), protocol);
+    }
+
+    /// Adds a custom header to the request.
+    pub fn add_header(&mut self, name: Cow<'t, str>, value: Cow<'t, str>) {
+        let mut headers = self.extra_headers.take().unwrap_or(vec![]);
+        headers.push((name, value));
+        self.extra_headers = Some(headers);
+    }
 }
 
 impl From<Url> for Request<'static> {
@@ -74,7 +88,7 @@ impl<S: Read + Write> ClientHandshake<S> {
                 Sec-WebSocket-Key: {key}\r\n",
                 host = request.get_host(), path = request.get_path(), key = key).unwrap();
             if let Some(eh) = request.extra_headers {
-                for &(k, v) in eh {
+                for (k, v) in eh {
                     write!(req, "{}: {}\r\n", k, v).unwrap();
                 }
             }