diff --git a/.travis.yml b/.travis.yml
index bc4166459..31e88b8f5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,6 @@
 language: php
 php:
+  - 5.5
   - 5.6
   - 7.0
 before_script:
diff --git a/composer.json b/composer.json
index 804173c28..9876a1f7e 100644
--- a/composer.json
+++ b/composer.json
@@ -6,13 +6,13 @@
 		"preferred-install": "source"
 	},
 	"require": {
-		"php": "^5.6|^7.0",
+		"php": "^5.5|^5.6|^7.0",
 		"jakub-onderka/php-parallel-lint": "~0.8"
 	},
 	"require-dev": {
 		"consistence/coding-standard": "^0.8",
 		"phing/phing": "^2.9",
-		"phpunit/phpunit": "^5.0",
+		"phpunit/phpunit": "^4.0",
 		"satooshi/php-coveralls": "dev-master",
 		"squizlabs/php_codesniffer": "2.5.0 as 2.3.4"
 	},