diff --git a/.travis.yml b/.travis.yml
index 0bb23a4a..069d8bec 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,6 +18,7 @@ matrix:
     - php: 7.1
     - php: 'nightly'
     - php: hhvm
+      dist: trusty
   allow_failures:
     - php: 'nightly'
 
diff --git a/composer.json b/composer.json
index c42f2178..9dc00051 100644
--- a/composer.json
+++ b/composer.json
@@ -41,9 +41,8 @@
     },
     "require-dev": {
         "json-schema/JSON-Schema-Test-Suite": "1.2.0",
-        "phpunit/phpunit": "^4.8.22",
         "friendsofphp/php-cs-fixer": "^2.1",
-        "phpdocumentor/phpdocumentor": "^2.7"
+        "phpunit/phpunit": "^4.8.22"
     },
     "autoload": {
         "psr-4": { "JsonSchema\\": "src/JsonSchema/" }