diff --git a/.travis.yml b/.travis.yml
index 64cadf62..9f61c021 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,20 +1,34 @@
 language: php
 
 php:
+  - 5.6
+  - 7.0
   - 7.1
   - 7.2
 
+# This triggers builds to run on the new TravisCI infrastructure.
+# See: http://docs.travis-ci.com/user/workers/container-based-infrastructure/
+sudo: false
+
+## Cache composer
+cache:
+  directories:
+    - $HOME/.composer/cache
+
 env:
-  - SYMFONY_VERSION="2.1"
-  - SYMFONY_VERSION="2.*"
-  - SYMFONY_VERSION="3.0"
-  - SYMFONY_VERSION="3.*"
-  - SYMFONY_VERSION="4.0"
-  - SYMFONY_VERSION="4.*"
+  global:
+    - symfony="*"
+
+matrix:
+  include:
+    - php: 5.6
+      env: symfony="^2.1"
+    - php: 5.6
+      env: symfony="^3"
+    - php: 7.1
+      env: symfony="^4"
 
-before_script:
-  - composer self-update
-  - composer --version
-  - composer require symfony/http-foundation:${SYMFONY_VERSION} --no-update
+install:
+  - if [[ $symfony != '*' ]]; then travis_retry composer require symfony/http-foundation:${symfony} --no-update --no-interaction; fi
 
 script: composer install --prefer-dist --no-interaction
diff --git a/README.md b/README.md
index cbe9056f..b4a1ae2f 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@
 [![Latest Stable Version](https://poser.pugx.org/omnipay/omnipay/version)](https://packagist.org/packages/omnipay/omnipay)
 [![Total Downloads](https://poser.pugx.org/omnipay/omnipay/d/total)](https://packagist.org/packages/omnipay/omnipay)
 
-Omnipay is a payment processing library for PHP 7.1+. It has been designed based on
+Omnipay is a payment processing library for PHP. It has been designed based on
 ideas from [Active Merchant](http://activemerchant.org/), plus experience implementing
 dozens of gateways for [CI Merchant]. It has a clear and consistent API,
 is fully unit tested, and even comes with an example application to get you started.
diff --git a/composer.json b/composer.json
index 4b09ba93..cec8accd 100644
--- a/composer.json
+++ b/composer.json
@@ -64,7 +64,7 @@
         }
     ],
     "require": {
-        "php": "^7.1",
+        "php": "^5.6|^7",
         "omnipay/common": "^3",
         "php-http/guzzle6-adapter": "^1.1"
     },