diff --git a/src/Composer/Json/JsonManipulator.php b/src/Composer/Json/JsonManipulator.php
index 7099b7ffd..901d40cc0 100644
--- a/src/Composer/Json/JsonManipulator.php
+++ b/src/Composer/Json/JsonManipulator.php
@@ -92,8 +92,7 @@ class JsonManipulator
 
         if (true === $sortPackages) {
             $requirements = json_decode($links, true);
-
-            ksort($requirements);
+            $this->sortPackages($requirements);
             $links = $this->format($requirements);
         }
 
@@ -102,6 +101,40 @@ class JsonManipulator
         return true;
     }
 
+    /**
+     * Sorts packages by importance (platform packages first, then PHP dependencies) and alphabetically.
+     *
+     * @link https://getcomposer.org/doc/02-libraries.md#platform-packages
+     *
+     * @param array $packages
+     */
+    private function sortPackages(array &$packages = array())
+    {
+        $prefix = function ($requirement) {
+            return preg_replace(
+                array(
+                    '/^php$/',
+                    '/^hhvm$/',
+                    '/^ext-\w+$/',
+                    '/^lib-\w+$/',
+                    '/^.+$/',
+                ),
+                array(
+                    '0-$0',
+                    '1-$0',
+                    '2-$0',
+                    '3-$0',
+                    '4-$0',
+                ),
+                $requirement
+            );
+        };
+
+        uksort($packages, function ($a, $b) use ($prefix) {
+            return strcmp($prefix($a), $prefix($b));
+        });
+    }
+
     public function addRepository($name, $config)
     {
         return $this->addSubNode('repositories', $name, $config);
diff --git a/tests/Composer/Test/Json/JsonManipulatorTest.php b/tests/Composer/Test/Json/JsonManipulatorTest.php
index a2054e719..b56f4bc0d 100644
--- a/tests/Composer/Test/Json/JsonManipulatorTest.php
+++ b/tests/Composer/Test/Json/JsonManipulatorTest.php
@@ -332,6 +332,34 @@ class JsonManipulatorTest extends \PHPUnit_Framework_TestCase
 }
 '
             ),
+            array(
+                '{
+    "require": {
+        "foo": "baz",
+        "ext-mcrypt": "*",
+        "ext-gd": "*",
+        "lib-foo": "*",
+        "hhvm": "*",
+        "php": ">=5.5"
+    }
+}',
+                'require',
+                'igorw/retry',
+                '*',
+                true,
+                '{
+    "require": {
+        "php": ">=5.5",
+        "hhvm": "*",
+        "ext-gd": "*",
+        "ext-mcrypt": "*",
+        "lib-foo": "*",
+        "foo": "baz",
+        "igorw/retry": "*"
+    }
+}
+',
+            ),
         );
     }