diff --git a/Cargo.toml b/Cargo.toml
index cd321bc..2814a33 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,7 +2,7 @@
 name = "hyper-openssl"
 version = "0.10.0"
 authors = ["Steven Fackler <sfackler@gmail.com>"]
-edition = "2018"
+edition = "2021"
 description = "Hyper TLS support via OpenSSL"
 license = "MIT/Apache-2.0"
 repository = "https://github.com/sfackler/hyper-openssl"
@@ -27,6 +27,7 @@ client-legacy = [
     "hyper-util?/client-legacy",
 ]
 
+tokio = ["hyper-util?/tokio"]
 
 [dependencies]
 http = { version = "1.0.0", optional = true }
diff --git a/src/client/legacy.rs b/src/client/legacy.rs
index 96a114d..fade8f1 100644
--- a/src/client/legacy.rs
+++ b/src/client/legacy.rs
@@ -4,7 +4,9 @@ use crate::SslStream;
 use http::uri::Scheme;
 use hyper::rt::{Read, ReadBufCursor, Write};
 use hyper::Uri;
-use hyper_util::client::legacy::connect::{Connected, Connection, HttpConnector};
+#[cfg(feature = "tokio")]
+use hyper_util::client::legacy::connect::HttpConnector;
+use hyper_util::client::legacy::connect::{Connected, Connection};
 use once_cell::sync::OnceCell;
 use openssl::error::ErrorStack;
 use openssl::ex_data::Index;
@@ -115,6 +117,7 @@ pub struct HttpsConnector<T> {
     inner: Inner,
 }
 
+#[cfg(feature = "tokio")]
 impl HttpsConnector<HttpConnector> {
     /// Creates a new `HttpsConnector` using default settings.
     ///