diff --git a/src/Composer/Repository/Vcs/GitLabDriver.php b/src/Composer/Repository/Vcs/GitLabDriver.php
index 042c1d8a9..ed91056d4 100644
--- a/src/Composer/Repository/Vcs/GitLabDriver.php
+++ b/src/Composer/Repository/Vcs/GitLabDriver.php
@@ -228,7 +228,24 @@ class GitLabDriver extends VcsDriver
      */
     public function getApiUrl()
     {
-        return $this->scheme.'://'.$this->originUrl.'/api/v3/projects/'.$this->owner.'%2F'.$this->repository;
+        return $this->scheme.'://'.$this->originUrl.'/api/v3/projects/'.$this->urlEncodeAll($this->owner).'%2F'.$this->urlEncodeAll($this->repository);
+    }
+
+    /**
+     * Urlencode all non alphanumeric characters. rawurlencode() can not be used as it does not encode `.`
+     *
+     * @param string $string
+     * @return string
+     */
+    private function urlEncodeAll($string)
+    {
+        $encoded = '';
+        for ($i = 0; isset($string[$i]); $i++) {
+            $character = $string[$i];
+            if (!ctype_alnum($character)) $character = '%' . sprintf('%02X', ord($character));
+            $encoded .= $character;
+        }
+        return $encoded;
     }
 
     /**
diff --git a/src/Composer/Util/Filesystem.php b/src/Composer/Util/Filesystem.php
index 847f8d8ee..2ac6a54fe 100644
--- a/src/Composer/Util/Filesystem.php
+++ b/src/Composer/Util/Filesystem.php
@@ -444,7 +444,8 @@ class Filesystem
         $prefix = '';
         $absolute = false;
 
-        if (preg_match('{^([0-9a-z]+:(?://(?:[a-z]:)?)?)}i', $path, $match)) {
+        // extract a prefix being a protocol://, protocol:, protocol://drive: or simply drive:
+        if (preg_match('{^( [0-9a-z]{2,}+: (?: // (?: [a-z]: )? )? | [a-z]: )}ix', $path, $match)) {
             $prefix = $match[1];
             $path = substr($path, strlen($prefix));
         }
diff --git a/tests/Composer/Test/Util/FilesystemTest.php b/tests/Composer/Test/Util/FilesystemTest.php
index 17297b916..4e60b0ce9 100644
--- a/tests/Composer/Test/Util/FilesystemTest.php
+++ b/tests/Composer/Test/Util/FilesystemTest.php
@@ -204,12 +204,18 @@ class FilesystemTest extends TestCase
             array('../foo', '../foo'),
             array('c:/foo/bar', 'c:/foo//bar'),
             array('C:/foo/bar', 'C:/foo/./bar'),
+            array('C:/foo/bar', 'C://foo//bar'),
+            array('C:/foo/bar', 'C:///foo//bar'),
             array('C:/bar', 'C:/foo/../bar'),
             array('/bar', '/foo/../bar/'),
             array('phar://c:/Foo', 'phar://c:/Foo/Bar/..'),
+            array('phar://c:/Foo', 'phar://c:///Foo/Bar/..'),
             array('phar://c:/', 'phar://c:/Foo/Bar/../../../..'),
             array('/', '/Foo/Bar/../../../..'),
             array('/', '/'),
+            array('/', '//'),
+            array('/', '///'),
+            array('/Foo', '///Foo'),
             array('c:/', 'c:\\'),
             array('../src', 'Foo/Bar/../../../src'),
             array('c:../b', 'c:.\\..\\a\\..\\b'),