diff --git a/Cargo.toml b/Cargo.toml
index d1bcfffc0..2b9210140 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -39,10 +39,10 @@ http = "0.2"
 hyper = { version = "0.14", features = ["client", "server", "tcp", "http2"] }
 hyper-rustls = { version = "0.24", optional = true, features = ["http2"] }
 hyper-tls = { version = "0.5.0", optional = true }
-itertools = "0.11"
+itertools = "0.12"
 log = "0.4"
 percent-encoding = "2"
-rustls = { version = "0.21.0", optional = true }
+rustls = { version = "^0.22.1", optional = true }
 rustls-pemfile = { version = "1.0.1", optional = true }
 seahash = "4"
 serde = {version = "1.0", features = ["derive"]}
diff --git a/src/service_account.rs b/src/service_account.rs
index ea73ac065..07f3dc865 100644
--- a/src/service_account.rs
+++ b/src/service_account.rs
@@ -22,11 +22,7 @@ use base64::Engine as _;
 use http::Uri;
 use hyper::client::connect::Connection;
 use hyper::header;
-use rustls::{
-    self,
-    sign::{self, SigningKey},
-    PrivateKey,
-};
+use rustls::{self, crypto::ring::sign, pki_types::PrivateKeyDer, sign::SigningKey};
 use serde::{Deserialize, Serialize};
 use time::OffsetDateTime;
 use tokio::io::{AsyncRead, AsyncWrite};
@@ -42,13 +38,13 @@ fn append_base64<T: AsRef<[u8]> + ?Sized>(s: &T, out: &mut String) {
 }
 
 /// Decode a PKCS8 formatted RSA key.
-fn decode_rsa_key(pem_pkcs8: &str) -> Result<PrivateKey, io::Error> {
+fn decode_rsa_key(pem_pkcs8: &str) -> Result<PrivateKeyDer, io::Error> {
     let private_keys = rustls_pemfile::pkcs8_private_keys(&mut pem_pkcs8.as_bytes());
 
     match private_keys {
         Ok(mut keys) if !keys.is_empty() => {
             keys.truncate(1);
-            Ok(rustls::PrivateKey(keys.remove(0)))
+            Ok(PrivateKeyDer::Pkcs8(keys.remove(0).into()))
         }
         Ok(_) => Err(io::Error::new(
             io::ErrorKind::InvalidInput,