diff --git a/CHANGELOG.md b/CHANGELOG.md
index d39cd92..a664941 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [1.6.4] - 2018-03-27
+### Changed
+- Update guzzlehttp/guzzle from 6.3.0 to 6.3.1
+
 ## [1.6.3] - 2017-12-11
 ### Changed
 - Fix return type if null in result company
diff --git a/composer.json b/composer.json
index 70f242a..288758b 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,7 @@
     "require": {
         "php": ">= 7.1",
         "psr/log": "~1.0",
-        "guzzlehttp/guzzle": "~6.0"
+        "guzzlehttp/guzzle": "6.3.1"
     },
     "require-dev": {
         "phpunit/phpunit": "~6.4",
diff --git a/composer.lock b/composer.lock
index f9a14a4..10f7926 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,20 +4,20 @@
         "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": "477060d0b2da5994d26a1e0c337d935a",
+    "content-hash": "4a3dc0c2c4316af01a7733331ba28ea8",
     "packages": [
         {
             "name": "guzzlehttp/guzzle",
-            "version": "6.3.0",
+            "version": "6.3.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/guzzle/guzzle.git",
-                "reference": "f4db5a78a5ea468d4831de7f0bf9d9415e348699"
+                "reference": "49e42e6539f775e80c74086a710a882e1d5a8111"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/guzzle/guzzle/zipball/f4db5a78a5ea468d4831de7f0bf9d9415e348699",
-                "reference": "f4db5a78a5ea468d4831de7f0bf9d9415e348699",
+                "url": "https://api.github.com/repos/guzzle/guzzle/zipball/49e42e6539f775e80c74086a710a882e1d5a8111",
+                "reference": "49e42e6539f775e80c74086a710a882e1d5a8111",
                 "shasum": ""
             },
             "require": {
@@ -27,7 +27,7 @@
             },
             "require-dev": {
                 "ext-curl": "*",
-                "phpunit/phpunit": "^4.0 || ^5.0",
+                "phpunit/phpunit": "^4.8.35 || ^5.7 || ^6.4",
                 "psr/log": "^1.0"
             },
             "suggest": {
@@ -36,7 +36,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "6.2-dev"
+                    "dev-master": "6.3-dev"
                 }
             },
             "autoload": {
@@ -69,7 +69,7 @@
                 "rest",
                 "web service"
             ],
-            "time": "2017-06-22T18:50:49+00:00"
+            "time": "2018-03-26T12:06:26+00:00"
         },
         {
             "name": "guzzlehttp/promises",