diff --git a/composer.json b/composer.json
index 2ac663d..4512336 100644
--- a/composer.json
+++ b/composer.json
@@ -10,7 +10,7 @@
         }
     ],
     "require": {
-        "symfony/yaml": "^4.1",
+        "symfony/yaml": "v3.1.10",
         "mikehaertl/php-tmpfile": "^1.1"
     },
     "autoload": {
diff --git a/composer.lock b/composer.lock
index 69034d7..0940472 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "507da316bc5196d904dfd3ccdcb680c8",
+    "content-hash": "f21bc326ada72dc5b7e1972d2e33e5ad",
     "packages": [
         {
             "name": "mikehaertl/php-tmpfile",
@@ -42,92 +42,27 @@
             ],
             "time": "2017-08-28T11:21:51+00:00"
         },
-        {
-            "name": "symfony/polyfill-ctype",
-            "version": "v1.8.0",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/symfony/polyfill-ctype.git",
-                "reference": "7cc359f1b7b80fc25ed7796be7d96adc9b354bae"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-ctype/zipball/7cc359f1b7b80fc25ed7796be7d96adc9b354bae",
-                "reference": "7cc359f1b7b80fc25ed7796be7d96adc9b354bae",
-                "shasum": ""
-            },
-            "require": {
-                "php": ">=5.3.3"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "1.8-dev"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Symfony\\Polyfill\\Ctype\\": ""
-                },
-                "files": [
-                    "bootstrap.php"
-                ]
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Symfony Community",
-                    "homepage": "https://symfony.com/contributors"
-                },
-                {
-                    "name": "Gert de Pagter",
-                    "email": "BackEndTea@gmail.com"
-                }
-            ],
-            "description": "Symfony polyfill for ctype functions",
-            "homepage": "https://symfony.com",
-            "keywords": [
-                "compatibility",
-                "ctype",
-                "polyfill",
-                "portable"
-            ],
-            "time": "2018-04-30T19:57:29+00:00"
-        },
         {
             "name": "symfony/yaml",
-            "version": "v4.1.3",
+            "version": "v3.1.10",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/yaml.git",
-                "reference": "46bc69aa91fc4ab78a96ce67873a6b0c148fd48c"
+                "reference": "752bc2a0dff0168742c92ec87261f7e09b7935fb"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/yaml/zipball/46bc69aa91fc4ab78a96ce67873a6b0c148fd48c",
-                "reference": "46bc69aa91fc4ab78a96ce67873a6b0c148fd48c",
+                "url": "https://api.github.com/repos/symfony/yaml/zipball/752bc2a0dff0168742c92ec87261f7e09b7935fb",
+                "reference": "752bc2a0dff0168742c92ec87261f7e09b7935fb",
                 "shasum": ""
             },
             "require": {
-                "php": "^7.1.3",
-                "symfony/polyfill-ctype": "~1.8"
-            },
-            "conflict": {
-                "symfony/console": "<3.4"
-            },
-            "require-dev": {
-                "symfony/console": "~3.4|~4.0"
-            },
-            "suggest": {
-                "symfony/console": "For validating YAML files using the lint command"
+                "php": ">=5.5.9"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "4.1-dev"
+                    "dev-master": "3.1-dev"
                 }
             },
             "autoload": {
@@ -154,7 +89,7 @@
             ],
             "description": "Symfony Yaml Component",
             "homepage": "https://symfony.com",
-            "time": "2018-07-26T11:24:31+00:00"
+            "time": "2017-01-21T17:01:39+00:00"
         }
     ],
     "packages-dev": [],