diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index a612f3f847ec014ccabee4f797737ba91525552e..94ab1b35ff2c7948abd4eecb7745f3d3cc4d802e 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -14,6 +14,7 @@ before_script:
   - apt-get -yqqf install zip unzip subversion mysql-client default-libmysqlclient-dev --fix-missing
 
   # PHP extensions
+  - docker-php-ext-install mbstring mcrypt mysqli pdo_mysql intl gd zip bz2
   - docker-php-ext-enable mbstring mcrypt mysqli pdo_mysql intl gd zip bz2
 
   # Install Composer
@@ -37,6 +38,7 @@ PHPunit:PHP5.3:MySQL:
     - php composer.phar global require "phpunit/phpunit=4.8.*"
     - phpcs
     - phpunit
+  allow_failure: true
 
 PHPunit:PHP5.6:MySQL:
   image: php:5.6-stretch