diff --git a/core/composer.json b/core/composer.json
index 6ad81658584abf87e8ed7b5c042fcf0ea1f1b9b7..fba8153e7fde007805423c7dff32a0b2293d5dce 100644
--- a/core/composer.json
+++ b/core/composer.json
@@ -21,7 +21,7 @@
     "twig/twig": "~1.20",
     "doctrine/common": "2.5.*",
     "doctrine/annotations": "1.2.*",
-    "guzzlehttp/guzzle": "~6.1.0",
+    "guzzlehttp/guzzle": "~6.1",
     "symfony-cmf/routing": "1.3.*",
     "easyrdf/easyrdf": "0.9.*",
     "phpunit/phpunit": "4.8.*",
diff --git a/core/composer.lock b/core/composer.lock
index d2d6b425e25e4db8cd43ad1b0422ebd566ac51c8..287e954afac7b43a11e998e6382c7179d4d37d78 100644
--- a/core/composer.lock
+++ b/core/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"
     ],
-    "hash": "eb73d28ce27162c98ea1a8865fddbf7d",
+    "hash": "641da18dedf5e11a7de3978b8fe619d6",
     "packages": [
         {
             "name": "behat/mink",
@@ -786,7 +786,7 @@
         },
         {
             "name": "guzzlehttp/guzzle",
-            "version": "dev-master",
+            "version": "6.1.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/guzzle/guzzle.git",
diff --git a/core/vendor/composer/installed.json b/core/vendor/composer/installed.json
index 47491938be73fe3fb1b233b6a295e7f8fbb464f3..256109d11dfc3896a9df6fd2b63ea4700b5c24fe 100644
--- a/core/vendor/composer/installed.json
+++ b/core/vendor/composer/installed.json
@@ -3422,8 +3422,8 @@
     },
     {
         "name": "guzzlehttp/guzzle",
-        "version": "dev-master",
-        "version_normalized": "9999999-dev",
+        "version": "6.1.0",
+        "version_normalized": "6.1.0.0",
         "source": {
             "type": "git",
             "url": "https://github.com/guzzle/guzzle.git",