diff --git a/src/async_impl/request.rs b/src/async_impl/request.rs
index 1522c1467..914ff13ab 100644
--- a/src/async_impl/request.rs
+++ b/src/async_impl/request.rs
@@ -1,7 +1,6 @@
 use std::convert::TryFrom;
 use std::fmt;
 use std::future::Future;
-use std::io::Write;
 use std::time::Duration;
 
 use serde::Serialize;
@@ -16,7 +15,6 @@ use super::response::Response;
 #[cfg(feature = "multipart")]
 use crate::header::CONTENT_LENGTH;
 use crate::header::{HeaderMap, HeaderName, HeaderValue, CONTENT_TYPE};
-use crate::util::base64;
 use crate::{Method, Url};
 use http::{request::Parts, Request as HttpRequest, Version};
 
@@ -251,16 +249,7 @@ impl RequestBuilder {
         U: fmt::Display,
         P: fmt::Display,
     {
-        let mut header_value = b"Basic ".to_vec();
-        {
-            let mut encoder = base64::encoder(&mut header_value);
-            // The unwraps here are fine because Vec::write* is infallible.
-            write!(encoder, "{}:", username).unwrap();
-            if let Some(password) = password {
-                write!(encoder, "{}", password).unwrap();
-            }
-        }
-
+        let header_value = crate::util::basic_auth(username, password);
         self.header_sensitive(crate::header::AUTHORIZATION, header_value, true)
     }
 
diff --git a/src/blocking/request.rs b/src/blocking/request.rs
index 4ac4a4b92..6dd7935e7 100644
--- a/src/blocking/request.rs
+++ b/src/blocking/request.rs
@@ -13,7 +13,6 @@ use super::body::{self, Body};
 use super::multipart;
 use super::Client;
 use crate::header::{HeaderMap, HeaderName, HeaderValue, CONTENT_TYPE};
-use crate::util::base64;
 use crate::{async_impl, Method, Url};
 
 /// A request which can be executed with `Client::execute()`.
@@ -266,12 +265,8 @@ impl RequestBuilder {
         U: fmt::Display,
         P: fmt::Display,
     {
-        let auth = match password {
-            Some(password) => format!("{}:{}", username, password),
-            None => format!("{}:", username),
-        };
-        let header_value = format!("Basic {}", base64::encode(&auth));
-        self.header_sensitive(crate::header::AUTHORIZATION, &*header_value, true)
+        let header_value = crate::util::basic_auth(username, password);
+        self.header_sensitive(crate::header::AUTHORIZATION, header_value, true)
     }
 
     /// Enable HTTP bearer authentication.
diff --git a/src/proxy.rs b/src/proxy.rs
index ee2447f4e..d2d434ee3 100644
--- a/src/proxy.rs
+++ b/src/proxy.rs
@@ -4,7 +4,6 @@ use std::net::SocketAddr;
 use std::sync::Arc;
 
 use crate::into_url::{IntoUrl, IntoUrlSealed};
-use crate::util::base64;
 use crate::Url;
 use http::{header::HeaderValue, Uri};
 use ipnet::IpNet;
@@ -763,12 +762,7 @@ impl fmt::Debug for Custom {
 }
 
 pub(crate) fn encode_basic_auth(username: &str, password: &str) -> HeaderValue {
-    let val = format!("{}:{}", username, password);
-    let mut header = format!("Basic {}", base64::encode(&val))
-        .parse::<HeaderValue>()
-        .expect("base64 is always valid HeaderValue");
-    header.set_sensitive(true);
-    header
+    crate::util::basic_auth(username, Some(password))
 }
 
 /// A helper trait to allow testing `Proxy::intercept` without having to
diff --git a/src/util.rs b/src/util.rs
index c30a15b6e..018db307f 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -1,22 +1,25 @@
-use crate::header::{Entry, HeaderMap, OccupiedEntry};
+use crate::header::{Entry, HeaderMap, HeaderValue, OccupiedEntry};
 
-pub(crate) mod base64 {
-    use std::io;
-
-    use base64::engine::GeneralPurpose;
+pub fn basic_auth<U, P>(username: U, password: Option<P>) -> HeaderValue
+where
+    U: std::fmt::Display,
+    P: std::fmt::Display,
+{
     use base64::prelude::BASE64_STANDARD;
     use base64::write::EncoderWriter;
+    use std::io::Write;
 
-    if_hyper! {
-        pub fn encode<T: AsRef<[u8]>>(input: T) -> String {
-            use base64::Engine;
-            BASE64_STANDARD.encode(input)
+    let mut buf = b"Basic ".to_vec();
+    {
+        let mut encoder = EncoderWriter::new(&mut buf, &BASE64_STANDARD);
+        let _ = write!(encoder, "{}:", username);
+        if let Some(password) = password {
+            let _ = write!(encoder, "{}", password);
         }
     }
-
-    pub fn encoder<'a, W: io::Write>(delegate: W) -> EncoderWriter<'a, GeneralPurpose, W> {
-        EncoderWriter::new(delegate, &BASE64_STANDARD)
-    }
+    let mut header = HeaderValue::from_bytes(&buf).expect("base64 is always valid HeaderValue");
+    header.set_sensitive(true);
+    header
 }
 
 // xor-shift
diff --git a/src/wasm/request.rs b/src/wasm/request.rs
index 46f4d13f8..2b0a6bec7 100644
--- a/src/wasm/request.rs
+++ b/src/wasm/request.rs
@@ -1,6 +1,5 @@
 use std::convert::TryFrom;
 use std::fmt;
-use std::io::Write;
 
 use bytes::Bytes;
 use http::{request::Parts, Method, Request as HttpRequest};
@@ -12,7 +11,6 @@ use web_sys::RequestCredentials;
 
 use super::{Body, Client, Response};
 use crate::header::{HeaderMap, HeaderName, HeaderValue, CONTENT_TYPE};
-use crate::util::base64;
 
 /// A request which can be executed with `Client::execute()`.
 pub struct Request {
@@ -214,16 +212,7 @@ impl RequestBuilder {
         U: fmt::Display,
         P: fmt::Display,
     {
-        let mut header_value = b"Basic ".to_vec();
-        {
-            let mut encoder = base64::encoder(&mut header_value);
-            // The unwraps here are fine because Vec::write* is infallible.
-            write!(encoder, "{}:", username).unwrap();
-            if let Some(password) = password {
-                write!(encoder, "{}", password).unwrap();
-            }
-        }
-
+        let header_value = crate::util::basic_auth(username, password);
         self.header(crate::header::AUTHORIZATION, header_value)
     }