diff --git a/composer.lock b/composer.lock
index d84dfe6..dc175d4 100644
--- a/composer.lock
+++ b/composer.lock
@@ -8,24 +8,25 @@
     "packages": [
         {
             "name": "amphp/amp",
-            "version": "v2.1.1",
+            "version": "v2.1.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/amphp/amp.git",
-                "reference": "7075ef7d74dbd32626bfd31c976b23055c3ade6a"
+                "reference": "f824f0df1da2cc042934fa267d7a227fff9276c9"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/amphp/amp/zipball/7075ef7d74dbd32626bfd31c976b23055c3ade6a",
-                "reference": "7075ef7d74dbd32626bfd31c976b23055c3ade6a",
+                "url": "https://api.github.com/repos/amphp/amp/zipball/f824f0df1da2cc042934fa267d7a227fff9276c9",
+                "reference": "f824f0df1da2cc042934fa267d7a227fff9276c9",
                 "shasum": ""
             },
             "require": {
                 "php": ">=7"
             },
             "require-dev": {
+                "amphp/php-cs-fixer-config": "dev-master",
                 "amphp/phpunit-util": "^1",
-                "friendsofphp/php-cs-fixer": "^2.3",
+                "ext-json": "*",
                 "phpstan/phpstan": "^0.8.5",
                 "phpunit/phpunit": "^6.0.9",
                 "react/promise": "^2"
@@ -80,7 +81,7 @@
                 "non-blocking",
                 "promise"
             ],
-            "time": "2018-12-11T10:31:37+00:00"
+            "time": "2019-05-31T18:42:02+00:00"
         },
         {
             "name": "amphp/artax",