diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e1c5662dfbc4d823a61208898d5b6eb09338c034..40347a6199dcaf944af0655904f9d829b7bb0e24 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -20,6 +20,9 @@ stages:
     paths:
       - "${COMPOSER_CACHE_DIR}"
 
+"5.6":
+  <<: *test
+
 "7.0":
   <<: *test
 
diff --git a/composer.json b/composer.json
index 728440a8b5ffd06fed4491e2b3b4aefac95144a7..b9f1cadc18b9008618202ab3e6d7bf3ea3b3b5c1 100644
--- a/composer.json
+++ b/composer.json
@@ -10,7 +10,7 @@
         }
     ],
     "require": {
-        "php": "^7.0",
+        "php": "^5.6 || ^7.0",
         "ext-json": "*",
         "friendsofphp/php-cs-fixer": "^2.13"
     },