diff --git a/Dockerfile b/Dockerfile
index f0c8b605..af646d09 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -7,7 +7,7 @@ RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys C300EE8C E5267A6C 0
 RUN apt-get update
 
 # Install PHP:
-RUN apt-get install -qy git-core php5-common php5-cli php5-curl php5-imap php5-mcrypt php5-mysqlnd
+RUN apt-get install -qy git-core php5-common php5-cli php5-curl php5-imap php5-mysqlnd
 
 # Give Git some fake user details to prevent it asking when trying to test merges:
 RUN git config --global user.name "PHPCI"
diff --git a/PHPCI/Command/InstallCommand.php b/PHPCI/Command/InstallCommand.php
index a4a0c4bb..29024090 100644
--- a/PHPCI/Command/InstallCommand.php
+++ b/PHPCI/Command/InstallCommand.php
@@ -118,7 +118,7 @@ class InstallCommand extends Command
         }
 
         // Check required extensions are present:
-        $requiredExtensions = array('PDO', 'pdo_mysql', 'mcrypt');
+        $requiredExtensions = array('PDO', 'pdo_mysql');
 
         foreach ($requiredExtensions as $extension) {
             if (!extension_loaded($extension)) {
diff --git a/PHPCI/Controller/PluginController.php b/PHPCI/Controller/PluginController.php
index 12aa18fc..31dfdf91 100644
--- a/PHPCI/Controller/PluginController.php
+++ b/PHPCI/Controller/PluginController.php
@@ -25,7 +25,6 @@ class PluginController extends \PHPCI\Controller
 {
     protected $required = array(
         'php',
-        'ext-mcrypt',
         'ext-pdo',
         'ext-pdo_mysql',
         'block8/b8framework',
diff --git a/composer.json b/composer.json
index dbced983..899bc083 100644
--- a/composer.json
+++ b/composer.json
@@ -30,7 +30,6 @@
 
     "require": {
         "php": ">=5.3.8",
-        "ext-mcrypt": "*",
         "ext-pdo": "*",
         "ext-pdo_mysql": "*",
         "block8/b8framework": "~1.0",