diff --git a/src/Composer/Util/StreamContextFactory.php b/src/Composer/Util/StreamContextFactory.php
index c0e6a5f25..df61b3c3e 100644
--- a/src/Composer/Util/StreamContextFactory.php
+++ b/src/Composer/Util/StreamContextFactory.php
@@ -34,21 +34,23 @@ final class StreamContextFactory
         // Handle system proxy
         if (isset($_SERVER['HTTP_PROXY']) || isset($_SERVER['http_proxy'])) {
             // Some systems seem to rely on a lowercased version instead...
-            $proxy = isset($_SERVER['http_proxy']) ? $_SERVER['http_proxy'] : $_SERVER['HTTP_PROXY'];
-            
-            $proxyURL = parse_url($proxy, PHP_URL_SCHEME) . "://";
-            $proxyURL .= parse_url($proxy, PHP_URL_HOST);
-            
-            $proxyPort = parse_url($proxy, PHP_URL_PORT);
-            
-            if (isset($proxyPort)) {
-                $proxyURL .= ":" . $proxyPort;
-            } else if ('http://' == substr($proxyURL, 0, 7)) {
+            $proxy = parse_url(isset($_SERVER['http_proxy']) ? $_SERVER['http_proxy'] : $_SERVER['HTTP_PROXY']);
+        } else {
+            $proxy = false;
+        }
+
+        if (false !== $proxy) {
+            $proxyURL = (isset($proxy['scheme']) ? $proxy['scheme'] : '') . '://';
+            $proxyURL .= isset($proxy['host']) ? $proxy['host'] : '';
+
+            if (isset($proxy['port'])) {
+                $proxyURL .= ":" . $proxy['port'];
+            } elseif ('http://' == substr($proxyURL, 0, 7)) {
                 $proxyURL .= ":80";
-            } else if ('https://' == substr($proxyURL, 0, 8)) {
+            } elseif ('https://' == substr($proxyURL, 0, 8)) {
                 $proxyURL .= ":443";
             }
-            
+
             // http(s):// is not supported in proxy
             $proxyURL = str_replace(array('http://', 'https://'), array('tcp://', 'ssl://'), $proxyURL);
 
@@ -60,18 +62,14 @@ final class StreamContextFactory
                 'proxy'           => $proxyURL,
                 'request_fulluri' => true,
             );
-            
-            // Extract authentication credentials from the proxy url
-            $user = parse_url($proxy, PHP_URL_USER);
-            $pass = parse_url($proxy, PHP_URL_PASS);
-            
-            if (isset($user)) {
-                $auth = $user;
-                if (isset($pass)) {
-                    $auth .= ":{$pass}";
+
+            if (isset($proxy['user'])) {
+                $auth = $proxy['user'];
+                if (isset($proxy['pass'])) {
+                    $auth .= ':' . $proxy['pass'];
                 }
                 $auth = base64_encode($auth);
-                
+
                 // Preserve headers if already set in default options 
                 if (isset($defaultOptions['http']['header'])) {
                     $defaultOptions['http']['header'] .=  "Proxy-Authorization: Basic {$auth}\r\n";
@@ -80,8 +78,9 @@ final class StreamContextFactory
                 }
             }
         }
+
         $options = array_merge_recursive($options, $defaultOptions);
-        
+
         return stream_context_create($options, $defaultParams);
     }
 }
diff --git a/tests/Composer/Test/Util/StreamContextFactoryTest.php b/tests/Composer/Test/Util/StreamContextFactoryTest.php
index 7fa74e0d9..dc60fe3bb 100644
--- a/tests/Composer/Test/Util/StreamContextFactoryTest.php
+++ b/tests/Composer/Test/Util/StreamContextFactoryTest.php
@@ -96,7 +96,7 @@ class StreamContextFactoryTest extends \PHPUnit_Framework_TestCase
         if (extension_loaded('openssl')) {
             $context = StreamContextFactory::getContext();
             $options = stream_context_get_options($context);
-            
+
             $this->assertEquals(array('http' => array(
                 'proxy' => $expected,
                 'request_fulluri' => true,