diff --git a/Cargo.toml b/Cargo.toml
index 329f2ae..7ae94ec 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,6 +16,8 @@ email = "^0.0"
 log = "^0.3"
 mime = "^0.2"
 openssl = "^0.9"
+base64 = "~0.5.0"
+hex = "^0.2.0"
 rustc-serialize = "^0.3"
 rust-crypto = "^0.2"
 time = "^0.1"
diff --git a/src/lib.rs b/src/lib.rs
index f9524b0..da66823 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -276,7 +276,8 @@
 extern crate log;
 #[macro_use]
 extern crate mime;
-extern crate rustc_serialize;
+extern crate base64;
+extern crate hex;
 extern crate crypto;
 extern crate time;
 extern crate uuid;
diff --git a/src/transport/smtp/authentication.rs b/src/transport/smtp/authentication.rs
index e7ac401..47ddcd0 100644
--- a/src/transport/smtp/authentication.rs
+++ b/src/transport/smtp/authentication.rs
@@ -3,7 +3,7 @@
 use crypto::hmac::Hmac;
 use crypto::mac::Mac;
 use crypto::md5::Md5;
-use rustc_serialize::hex::ToHex;
+use hex::ToHex;
 use std::fmt;
 use std::fmt::{Display, Formatter};
 use transport::smtp::NUL;
diff --git a/src/transport/smtp/client/mod.rs b/src/transport/smtp/client/mod.rs
index 69c98a2..0c62b4b 100644
--- a/src/transport/smtp/client/mod.rs
+++ b/src/transport/smtp/client/mod.rs
@@ -3,7 +3,7 @@
 use bufstream::BufStream;
 use openssl::ssl::SslContext;
 
-use rustc_serialize::base64::{self, FromBase64, ToBase64};
+use base64;
 use std::fmt::Debug;
 use std::io;
 use std::io::{BufRead, Read, Write};
@@ -204,9 +204,7 @@ impl<S: Connector + Timeout + Write + Read + Debug> Client<S> {
         if mechanism.supports_initial_response() {
             self.command(&format!("AUTH {} {}",
                                   mechanism,
-                                  try!(mechanism.response(username, password, None))
-                                      .as_bytes()
-                                      .to_base64(base64::STANDARD)))
+                                  base64::encode_config(try!(mechanism.response(username, password, None)).as_bytes(), base64::STANDARD)))
         } else {
             let encoded_challenge = match try!(self.command(&format!("AUTH {}", mechanism)))
                       .first_word() {
@@ -216,7 +214,7 @@ impl<S: Connector + Timeout + Write + Read + Debug> Client<S> {
 
             debug!("auth encoded challenge: {}", encoded_challenge);
 
-            let decoded_challenge = match encoded_challenge.from_base64() {
+            let decoded_challenge = match base64::decode(&encoded_challenge) {
                 Ok(challenge) => {
                     match String::from_utf8(challenge) {
                         Ok(value) => value,
@@ -231,11 +229,10 @@ impl<S: Connector + Timeout + Write + Read + Debug> Client<S> {
             let mut challenge_expected = 3;
 
             while challenge_expected > 0 {
-                let response = try!(self.command(&try!(mechanism.response(username,
+                let response = try!(self.command(&base64::encode_config(&try!(mechanism.response(username,
                                                                 password,
                                                                 Some(&decoded_challenge)))
-                                                          .as_bytes()
-                                                          .to_base64(base64::STANDARD)));
+                                                          .as_bytes(), base64::STANDARD)));
 
                 if !response.has_code(334) {
                     return Ok(response);
diff --git a/src/transport/smtp/error.rs b/src/transport/smtp/error.rs
index 942fb8e..4a0a29e 100644
--- a/src/transport/smtp/error.rs
+++ b/src/transport/smtp/error.rs
@@ -1,7 +1,7 @@
 //! Error and result type for SMTP clients
 
 use self::Error::*;
-use rustc_serialize::base64::FromBase64Error;
+use base64::DecodeError;
 use std::error::Error as StdError;
 use std::fmt;
 use std::fmt::{Display, Formatter};
@@ -23,7 +23,7 @@ pub enum Error {
     /// Error parsing a response
     ResponseParsing(&'static str),
     /// Error parsing a base64 string in response
-    ChallengeParsing(FromBase64Error),
+    ChallengeParsing(DecodeError),
     /// Error parsing UTF8in response
     Utf8Parsing(FromUtf8Error),
     /// Internal client error