diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 365523f..a343573 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,6 +9,7 @@ jobs:
       fail-fast: true
       matrix:
         rust:
+          - 1.60.0
           - stable
           - beta
           - nightly
@@ -30,6 +31,7 @@ jobs:
       fail-fast: true
       matrix:
         rust:
+          - 1.60.0
           - stable
           - beta
           - nightly
diff --git a/Cargo.toml b/Cargo.toml
index c4bbd2a..f81fd6e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,31 +19,31 @@ keywords = [
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-async-trait = { version = "^0.1.58", optional = true }
-base64 = { version = "^0.13.1", optional = true }
-bytes = { version = "^1.3.0", features = ["serde"], optional = true }
+async-trait = { version = "^0.1.66", optional = true }
+base64 = { version = "^0.21.0", optional = true }
+bytes = { version = "^1.4.0", features = ["serde"], optional = true }
 cidr = { version = "^0.2.1", optional = true }
 crypto-common = { version = "^0.1.6", optional = true }
 headers = { version = "^0.3.8", optional = true }
 hmac = { version = "^0.12.1", features = ["std"], optional = true }
-hyper = { version = "^0.14.23", default-features = false, optional = true }
+hyper = { version = "^0.14.24", default-features = false, optional = true }
 hyper-tls = { version = "^0.5.0", optional = true }
 hyper-proxy = { version = "^0.9.1", default-features = false, features = ["tls"], optional = true }
 lazy_static = { version = "^1.4.0", optional = true }
 log = { version = "^0.4.17", optional = true }
 prometheus = { version = "^0.13.3", optional = true }
-serde = { version = "^1.0.147", features = ["derive"], optional = true }
-serde_json = { version = "^1.0.88", features = [
+serde = { version = "^1.0.152", features = ["derive"], optional = true }
+serde_json = { version = "^1.0.94", features = [
     "preserve_order",
     "float_roundtrip",
 ], optional = true }
 sha2 = { version = "^0.10.6", optional = true }
-thiserror = { version = "^1.0.37", optional = true }
+thiserror = { version = "^1.0.39", optional = true }
 tracing = { version = "^0.1.37", optional = true }
 tracing-futures = { version = "^0.2.5", optional = true }
 url = { version = "^2.3.1", default-features = false, features = ["serde"], optional = true }
 urlencoding = { version = "^2.1.2", optional = true }
-uuid = { version = "^1.2.2", features = ["serde", "v4"], optional = true }
+uuid = { version = "^1.3.0", features = ["serde", "v4"], optional = true }
 
 [features]
 default = ["client", "proxy", "logging"]
diff --git a/rust-toolchain b/rust-toolchain
new file mode 100644
index 0000000..4d5fde5
--- /dev/null
+++ b/rust-toolchain
@@ -0,0 +1 @@
+1.60.0
diff --git a/src/client/mod.rs b/src/client/mod.rs
index e2ba226..f008f83 100644
--- a/src/client/mod.rs
+++ b/src/client/mod.rs
@@ -15,6 +15,7 @@ use std::{
 };
 
 use async_trait::async_trait;
+use base64::{engine::general_purpose::STANDARD as BASE64_ENGINE, Engine};
 use bytes::Buf;
 use crypto_common::InvalidLength;
 use hmac::{Hmac, Mac};
@@ -242,15 +243,6 @@ impl OAuth1 for Signer {
         params
     }
 
-    #[cfg_attr(feature = "trace", tracing::instrument)]
-    fn signing_key(&self) -> String {
-        format!(
-            "{}&{}",
-            urlencoding::encode(&self.credentials.consumer_secret.to_owned()),
-            urlencoding::encode(&self.credentials.secret.to_owned())
-        )
-    }
-
     #[cfg_attr(feature = "trace", tracing::instrument)]
     fn signature(&self, method: &str, endpoint: &str) -> Result<String, Self::Error> {
         let (host, query) = match endpoint.find(|c| '?' == c) {
@@ -294,7 +286,16 @@ impl OAuth1 for Signer {
         hasher.update(base.as_bytes());
 
         let digest = hasher.finalize().into_bytes();
-        Ok(base64::encode(digest.as_slice()))
+        Ok(BASE64_ENGINE.encode(digest.as_slice()))
+    }
+
+    #[cfg_attr(feature = "trace", tracing::instrument)]
+    fn signing_key(&self) -> String {
+        format!(
+            "{}&{}",
+            urlencoding::encode(&self.credentials.consumer_secret.to_owned()),
+            urlencoding::encode(&self.credentials.secret.to_owned())
+        )
     }
 }