diff --git a/Cargo.toml b/Cargo.toml
index 3134e48..16ddea4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -29,6 +29,7 @@ imap-proto = "0.8"
 nom = "4.0"
 base64 = "0.10"
 chrono = "0.4"
+lazy_static = "1.4"
 
 [dev-dependencies]
 lettre = "0.9"
diff --git a/src/client.rs b/src/client.rs
index 9e0a02c..8ec0db9 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -6,6 +6,7 @@ use std::collections::HashSet;
 use std::io::{Read, Write};
 use std::net::{TcpStream, ToSocketAddrs};
 use std::ops::{Deref, DerefMut};
+use std::str;
 use std::sync::mpsc;
 
 use super::authenticator::Authenticator;
@@ -346,13 +347,19 @@ impl<T: Read + Write> Client<T> {
             ok_or_unauth_client_err!(self.readline(&mut line), self);
 
             if line.starts_with(b"+ ") {
-                let data = ok_or_unauth_client_err!(
-                    parse_authenticate_response(String::from_utf8(line).unwrap()),
+                let line_str = ok_or_unauth_client_err!(
+                    match str::from_utf8(line.as_slice()) {
+                        Ok(line_str) => Ok(line_str),
+                        Err(e) => Err(Error::Parse(ParseError::DataNotUtf8(line, e))),
+                    },
                     self
                 );
+                let data = ok_or_unauth_client_err!(parse_authenticate_response(line_str), self);
                 let challenge = ok_or_unauth_client_err!(
-                    base64::decode(data.as_str())
-                        .map_err(|e| Error::Parse(ParseError::Authentication(data, Some(e)))),
+                    base64::decode(data).map_err(|e| Error::Parse(ParseError::Authentication(
+                        data.to_string(),
+                        Some(e)
+                    ))),
                     self
                 );
                 let raw_response = &authenticator.process(&challenge);
diff --git a/src/error.rs b/src/error.rs
index 50ba919..3acc429 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -5,7 +5,7 @@ use std::fmt;
 use std::io::Error as IoError;
 use std::net::TcpStream;
 use std::result;
-use std::string::FromUtf8Error;
+use std::str::Utf8Error;
 
 use base64::DecodeError;
 use bufstream::IntoInnerError as BufError;
@@ -111,7 +111,7 @@ impl StdError for Error {
             Error::Io(ref e) => Some(e),
             Error::Tls(ref e) => Some(e),
             Error::TlsHandshake(ref e) => Some(e),
-            Error::Parse(ParseError::DataNotUtf8(ref e)) => Some(e),
+            Error::Parse(ParseError::DataNotUtf8(_, ref e)) => Some(e),
             _ => None,
         }
     }
@@ -127,7 +127,7 @@ pub enum ParseError {
     /// The client could not find or decode the server's authentication challenge.
     Authentication(String, Option<DecodeError>),
     /// The client receive data that was not UTF-8 encoded.
-    DataNotUtf8(FromUtf8Error),
+    DataNotUtf8(Vec<u8>, Utf8Error),
 }
 
 impl fmt::Display for ParseError {
@@ -144,7 +144,7 @@ impl StdError for ParseError {
             ParseError::Invalid(_) => "Unable to parse status response",
             ParseError::Unexpected(_) => "Encountered unexpected parsed response",
             ParseError::Authentication(_, _) => "Unable to parse authentication response",
-            ParseError::DataNotUtf8(_) => "Unable to parse data as UTF-8 text",
+            ParseError::DataNotUtf8(_, _) => "Unable to parse data as UTF-8 text",
         }
     }
 
diff --git a/src/parse.rs b/src/parse.rs
index a2de763..dbcb27f 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -1,4 +1,5 @@
 use imap_proto::{self, MailboxDatum, Response};
+use lazy_static::lazy_static;
 use regex::Regex;
 use std::collections::HashSet;
 use std::sync::mpsc;
@@ -6,15 +7,19 @@ use std::sync::mpsc;
 use super::error::{Error, ParseError, Result};
 use super::types::*;
 
-pub fn parse_authenticate_response(line: String) -> Result<String> {
-    let authenticate_regex = Regex::new("^\\+ (.*)\r\n").unwrap();
+lazy_static! {
+    static ref AUTH_RESP_REGEX: Regex = Regex::new("^\\+ (.*)\r\n").unwrap();
+}
 
-    if let Some(cap) = authenticate_regex.captures_iter(line.as_str()).next() {
+pub fn parse_authenticate_response(line: &str) -> Result<&str> {
+    if let Some(cap) = AUTH_RESP_REGEX.captures_iter(line).next() {
         let data = cap.get(1).map(|x| x.as_str()).unwrap_or("");
-        return Ok(String::from(data));
+        return Ok(data);
     }
-
-    Err(Error::Parse(ParseError::Authentication(line, None)))
+    Err(Error::Parse(ParseError::Authentication(
+        line.to_string(),
+        None,
+    )))
 }
 
 enum MapOrNot<T> {