diff --git a/composer.lock b/composer.lock
index 17ff031..7bd20ac 100644
--- a/composer.lock
+++ b/composer.lock
@@ -67,16 +67,16 @@
         },
         {
             "name": "composer/composer",
-            "version": "1.5.2",
+            "version": "1.6.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/composer/composer.git",
-                "reference": "c639623fa2178b404ed4bab80f0d1263853fa4ae"
+                "reference": "87f845d1c14aa22819c51b367ad7e07823f2e2ec"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/composer/composer/zipball/c639623fa2178b404ed4bab80f0d1263853fa4ae",
-                "reference": "c639623fa2178b404ed4bab80f0d1263853fa4ae",
+                "url": "https://api.github.com/repos/composer/composer/zipball/87f845d1c14aa22819c51b367ad7e07823f2e2ec",
+                "reference": "87f845d1c14aa22819c51b367ad7e07823f2e2ec",
                 "shasum": ""
             },
             "require": {
@@ -89,13 +89,13 @@
                 "seld/cli-prompt": "^1.0",
                 "seld/jsonlint": "^1.4",
                 "seld/phar-utils": "^1.0",
-                "symfony/console": "^2.7 || ^3.0",
-                "symfony/filesystem": "^2.7 || ^3.0",
-                "symfony/finder": "^2.7 || ^3.0",
-                "symfony/process": "^2.7 || ^3.0"
+                "symfony/console": "^2.7 || ^3.0 || ^4.0",
+                "symfony/filesystem": "^2.7 || ^3.0 || ^4.0",
+                "symfony/finder": "^2.7 || ^3.0 || ^4.0",
+                "symfony/process": "^2.7 || ^3.0 || ^4.0"
             },
             "require-dev": {
-                "phpunit/phpunit": "^4.5 || ^5.0.5",
+                "phpunit/phpunit": "^4.8.35 || ^5.7",
                 "phpunit/phpunit-mock-objects": "^2.3 || ^3.0"
             },
             "suggest": {
@@ -109,7 +109,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.5-dev"
+                    "dev-master": "1.6-dev"
                 }
             },
             "autoload": {
@@ -140,7 +140,7 @@
                 "dependency",
                 "package"
             ],
-            "time": "2017-09-11T14:59:26+00:00"
+            "time": "2018-01-04T11:03:23+00:00"
         },
         {
             "name": "composer/semver",