diff --git a/Cargo.toml b/Cargo.toml
index 07ff2fd..3010f0c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 
 name = "smtp"
-version = "0.0.13"
+version = "0.0.15"
 description = "Simple SMTP client"
 readme = "README.md"
 documentation = "http://amousset.github.io/rust-smtp/smtp/"
diff --git a/src/client/authentication.rs b/src/client/authentication.rs
index 4984596..b3c8a5c 100644
--- a/src/client/authentication.rs
+++ b/src/client/authentication.rs
@@ -16,6 +16,7 @@ use crypto::md5::Md5;
 use crypto::mac::Mac;
 
 use NUL;
+use error::Error;
 
 /// Returns a PLAIN mecanism response
 pub fn plain(username: &str, password: &str) -> String {
@@ -23,14 +24,16 @@ pub fn plain(username: &str, password: &str) -> String {
 }
 
 /// Returns a CRAM-MD5 mecanism response
-pub fn cram_md5(username: &str, password: &str, encoded_challenge: &str) -> String {
-    // TODO manage errors
-    let challenge = encoded_challenge.from_base64().unwrap();
+pub fn cram_md5(username: &str, password: &str, encoded_challenge: &str) -> Result<String, Error> {
+    let challenge = match encoded_challenge.from_base64() {
+        Ok(challenge) => challenge,
+        Err(error) => return Err(Error::ChallengeParsingError(error)),
+    };
 
     let mut hmac = Hmac::new(Md5::new(), password.as_bytes());
     hmac.input(&challenge);
 
-    format!("{} {}", username, hmac.result().code().to_hex()).as_bytes().to_base64(base64::STANDARD)
+    Ok(format!("{} {}", username, hmac.result().code().to_hex()).as_bytes().to_base64(base64::STANDARD))
 }
 
 #[cfg(test)]
@@ -45,7 +48,7 @@ mod test {
     #[test]
     fn test_cram_md5() {
         assert_eq!(cram_md5("alice", "wonderland",
-            "PDE3ODkzLjEzMjA2NzkxMjNAdGVzc2VyYWN0LnN1c2FtLmluPg=="),
+            "PDE3ODkzLjEzMjA2NzkxMjNAdGVzc2VyYWN0LnN1c2FtLmluPg==").unwrap(),
             "YWxpY2UgNjRiMmE0M2MxZjZlZDY4MDZhOTgwOTE0ZTIzZTc1ZjA=");
     }
 }
diff --git a/src/client/mod.rs b/src/client/mod.rs
index b9013c5..5dbd5c4 100644
--- a/src/client/mod.rs
+++ b/src/client/mod.rs
@@ -16,7 +16,7 @@ use std::io::{BufRead, Read, Write};
 use bufstream::BufStream;
 
 use response::ResponseParser;
-use error::SmtpResult;
+use error::{Error, SmtpResult};
 use client::net::{Connector, SmtpStream};
 use client::authentication::{plain, cram_md5};
 use {CRLF, MESSAGE_ENDING};
@@ -175,8 +175,14 @@ impl<S: Connector + Write + Read = SmtpStream> Client<S> {
 
     /// Sends an AUTH command with CRAM-MD5 mecanism
     pub fn auth_cram_md5(&mut self, username: &str, password: &str) -> SmtpResult {
-        let encoded_challenge = try!(self.command("AUTH CRAM-MD5")).first_word().expect("No challenge");
-        self.command(&format!("AUTH CRAM-MD5 {}", cram_md5(username, password, &encoded_challenge)))
+        let encoded_challenge = match try!(self.command("AUTH CRAM-MD5")).first_word() {
+            Some(challenge) => challenge,
+            None => return Err(Error::ResponseParsingError("Could not read CRAM challenge")),
+        };
+
+        let cram_response = try!(cram_md5(username, password, &encoded_challenge));
+
+        self.command(&format!("AUTH CRAM-MD5 {}", cram_response))
     }
 
     /// Sends the message content
diff --git a/src/email.rs b/src/email.rs
index 4a2b4a9..cfbf6f7 100644
--- a/src/email.rs
+++ b/src/email.rs
@@ -103,11 +103,10 @@ impl EmailBuilder {
             message_id: current_message,
         };
 
-        email.message.headers.insert(
-            Header::new_with_value("Message-ID".to_string(),
-                format!("<{}@rust-smtp>", current_message)
-            ).unwrap()
-        );
+        match Header::new_with_value("Message-ID".to_string(), format!("<{}@rust-smtp>", current_message)) {
+            Ok(header) => email.message.headers.insert(header),
+            Err(_) => (),
+        }
 
         EmailBuilder {
             content: email,
diff --git a/src/error.rs b/src/error.rs
index e7f2fa6..a7ad0fa 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -15,6 +15,7 @@ use std::fmt::{Display, Formatter};
 use std::fmt;
 
 use response::{Severity, Response};
+use serialize::base64::FromBase64Error;
 use self::Error::*;
 
 /// An enum of all error kinds.
@@ -30,6 +31,8 @@ pub enum Error {
     PermanentError(Response),
     /// Error parsing a response
     ResponseParsingError(&'static str),
+    /// Error parsing a base64 string in response
+    ChallengeParsingError(FromBase64Error),
     /// Internal client error
     ClientError(&'static str),
     /// DNS resolution error
@@ -50,6 +53,7 @@ impl StdError for Error {
             TransientError(_) => "a transient error occured during the SMTP transaction",
             PermanentError(_) => "a permanent error occured during the SMTP transaction",
             ResponseParsingError(_) => "an error occured while parsing an SMTP response",
+            ChallengeParsingError(_) => "an error occured while parsing a CRAM-MD5 challenge",
             ResolutionError => "Could no resolve hostname",
             ClientError(_) => "an unknown error occured",
             IoError(_) => "an I/O error occured",