diff --git a/src/Composer/Installer/InstallationManager.php b/src/Composer/Installer/InstallationManager.php
index c015bd9f9..f2fd405c8 100644
--- a/src/Composer/Installer/InstallationManager.php
+++ b/src/Composer/Installer/InstallationManager.php
@@ -16,6 +16,7 @@ use Composer\Package\PackageInterface;
 use Composer\Package\AliasPackage;
 use Composer\Repository\RepositoryInterface;
 use Composer\Repository\NotifiableRepositoryInterface;
+use Composer\Repository\InstalledRepositoryInterface;
 use Composer\DependencyResolver\Operation\OperationInterface;
 use Composer\DependencyResolver\Operation\InstallOperation;
 use Composer\DependencyResolver\Operation\UpdateOperation;
@@ -96,12 +97,12 @@ class InstallationManager
     /**
      * Checks whether provided package is installed in one of the registered installers.
      *
-     * @param   RepositoryInterface    $repo    repository in which to check
+     * @param   InstalledRepositoryInterface    $repo    repository in which to check
      * @param   PackageInterface    $package    package instance
      *
      * @return  Boolean
      */
-    public function isPackageInstalled(RepositoryInterface $repo, PackageInterface $package)
+    public function isPackageInstalled(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         return $this->getInstaller($package->getType())->isInstalled($repo, $package);
     }
diff --git a/src/Composer/Installer/InstallerInstaller.php b/src/Composer/Installer/InstallerInstaller.php
index 9519d384b..98e941d4c 100644
--- a/src/Composer/Installer/InstallerInstaller.php
+++ b/src/Composer/Installer/InstallerInstaller.php
@@ -15,7 +15,7 @@ namespace Composer\Installer;
 use Composer\IO\IOInterface;
 use Composer\Autoload\AutoloadGenerator;
 use Composer\Downloader\DownloadManager;
-use Composer\Repository\WritableRepositoryInterface;
+use Composer\Repository\InstalledRepositoryInterface;
 use Composer\DependencyResolver\Operation\OperationInterface;
 use Composer\Package\PackageInterface;
 
@@ -35,7 +35,7 @@ class InstallerInstaller extends LibraryInstaller
      * @param   DownloadManager             $dm         download manager
      * @param   IOInterface                 $io         io instance
      * @param   InstallationManager         $im         installation manager
-     * @param   array                       $localRepositories array of WritableRepositoryInterface
+     * @param   array                       $localRepositories array of InstalledRepositoryInterface
      */
     public function __construct($vendorDir, $binDir, DownloadManager $dm, IOInterface $io, InstallationManager $im, array $localRepositories)
     {
@@ -54,7 +54,7 @@ class InstallerInstaller extends LibraryInstaller
     /**
      * {@inheritDoc}
      */
-    public function install(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function install(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         $extra = $package->getExtra();
         if (empty($extra['class'])) {
@@ -68,7 +68,7 @@ class InstallerInstaller extends LibraryInstaller
     /**
      * {@inheritDoc}
      */
-    public function update(WritableRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target)
+    public function update(InstalledRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target)
     {
         $extra = $target->getExtra();
         if (empty($extra['class'])) {
diff --git a/src/Composer/Installer/InstallerInterface.php b/src/Composer/Installer/InstallerInterface.php
index 3716ec6df..099b46fdc 100644
--- a/src/Composer/Installer/InstallerInterface.php
+++ b/src/Composer/Installer/InstallerInterface.php
@@ -14,7 +14,7 @@ namespace Composer\Installer;
 
 use Composer\DependencyResolver\Operation\OperationInterface;
 use Composer\Package\PackageInterface;
-use Composer\Repository\WritableRepositoryInterface;
+use Composer\Repository\InstalledRepositoryInterface;
 
 /**
  * Interface for the package installation manager.
@@ -35,39 +35,39 @@ interface InstallerInterface
     /**
      * Checks that provided package is installed.
      *
-     * @param   WritableRepositoryInterface $repo    repository in which to check
+     * @param   InstalledRepositoryInterface $repo    repository in which to check
      * @param   PackageInterface    $package    package instance
      *
      * @return  Boolean
      */
-    function isInstalled(WritableRepositoryInterface $repo, PackageInterface $package);
+    function isInstalled(InstalledRepositoryInterface $repo, PackageInterface $package);
 
     /**
      * Installs specific package.
      *
-     * @param   WritableRepositoryInterface $repo    repository in which to check
+     * @param   InstalledRepositoryInterface $repo    repository in which to check
      * @param   PackageInterface    $package    package instance
      */
-    function install(WritableRepositoryInterface $repo, PackageInterface $package);
+    function install(InstalledRepositoryInterface $repo, PackageInterface $package);
 
     /**
      * Updates specific package.
      *
-     * @param   WritableRepositoryInterface $repo    repository in which to check
+     * @param   InstalledRepositoryInterface $repo    repository in which to check
      * @param   PackageInterface    $initial    already installed package version
      * @param   PackageInterface    $target     updated version
      *
      * @throws  InvalidArgumentException        if $from package is not installed
      */
-    function update(WritableRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target);
+    function update(InstalledRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target);
 
     /**
      * Uninstalls specific package.
      *
-     * @param   WritableRepositoryInterface $repo    repository in which to check
+     * @param   InstalledRepositoryInterface $repo    repository in which to check
      * @param   PackageInterface    $package    package instance
      */
-    function uninstall(WritableRepositoryInterface $repo, PackageInterface $package);
+    function uninstall(InstalledRepositoryInterface $repo, PackageInterface $package);
 
     /**
      * Returns the installation path of a package
diff --git a/src/Composer/Installer/LibraryInstaller.php b/src/Composer/Installer/LibraryInstaller.php
index baff5fdeb..9e321df19 100644
--- a/src/Composer/Installer/LibraryInstaller.php
+++ b/src/Composer/Installer/LibraryInstaller.php
@@ -14,7 +14,7 @@ namespace Composer\Installer;
 
 use Composer\IO\IOInterface;
 use Composer\Downloader\DownloadManager;
-use Composer\Repository\WritableRepositoryInterface;
+use Composer\Repository\InstalledRepositoryInterface;
 use Composer\DependencyResolver\Operation\OperationInterface;
 use Composer\Package\PackageInterface;
 use Composer\Util\Filesystem;
@@ -65,7 +65,7 @@ class LibraryInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function isInstalled(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function isInstalled(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         return $repo->hasPackage($package) && is_readable($this->getInstallPath($package));
     }
@@ -73,7 +73,7 @@ class LibraryInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function install(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function install(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         $this->initializeVendorDir();
         $downloadPath = $this->getInstallPath($package);
@@ -93,7 +93,7 @@ class LibraryInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function update(WritableRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target)
+    public function update(InstalledRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target)
     {
         if (!$repo->hasPackage($initial)) {
             throw new \InvalidArgumentException('Package is not installed: '.$initial);
@@ -114,7 +114,7 @@ class LibraryInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function uninstall(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function uninstall(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         if (!$repo->hasPackage($package)) {
             // TODO throw exception again here, when update is fixed and we don't have to remove+install (see #125)
diff --git a/src/Composer/Installer/MetapackageInstaller.php b/src/Composer/Installer/MetapackageInstaller.php
index 9dcdbd3d0..e0d19ab6e 100644
--- a/src/Composer/Installer/MetapackageInstaller.php
+++ b/src/Composer/Installer/MetapackageInstaller.php
@@ -12,7 +12,7 @@
 
 namespace Composer\Installer;
 
-use Composer\Repository\WritableRepositoryInterface;
+use Composer\Repository\InstalledRepositoryInterface;
 use Composer\Package\PackageInterface;
 
 /**
@@ -33,7 +33,7 @@ class MetapackageInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function isInstalled(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function isInstalled(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         return $repo->hasPackage($package);
     }
@@ -41,7 +41,7 @@ class MetapackageInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function install(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function install(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         $repo->addPackage(clone $package);
     }
@@ -49,7 +49,7 @@ class MetapackageInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function update(WritableRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target)
+    public function update(InstalledRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target)
     {
         if (!$repo->hasPackage($initial)) {
             throw new \InvalidArgumentException('Package is not installed: '.$initial);
@@ -62,7 +62,7 @@ class MetapackageInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function uninstall(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function uninstall(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         if (!$repo->hasPackage($package)) {
             // TODO throw exception again here, when update is fixed and we don't have to remove+install (see #125)
diff --git a/src/Composer/Installer/ProjectInstaller.php b/src/Composer/Installer/ProjectInstaller.php
index e41e8bb64..274d8e5ae 100644
--- a/src/Composer/Installer/ProjectInstaller.php
+++ b/src/Composer/Installer/ProjectInstaller.php
@@ -15,7 +15,7 @@ namespace Composer\Installer;
 use Composer\DependencyResolver\Operation\OperationInterface;
 use Composer\Package\PackageInterface;
 use Composer\Downloader\DownloadManager;
-use Composer\Repository\WritableRepositoryInterface;
+use Composer\Repository\InstalledRepositoryInterface;
 
 /**
  * Project Installer is used to install a single package into a directory as
@@ -48,7 +48,7 @@ class ProjectInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function isInstalled(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function isInstalled(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         return false;
     }
@@ -56,7 +56,7 @@ class ProjectInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function install(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function install(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         $installPath = $this->installPath;
         if (file_exists($installPath)) {
@@ -72,7 +72,7 @@ class ProjectInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function update(WritableRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target)
+    public function update(InstalledRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target)
     {
         throw new \InvalidArgumentException("not supported");
     }
@@ -80,7 +80,7 @@ class ProjectInstaller implements InstallerInterface
     /**
      * {@inheritDoc}
      */
-    public function uninstall(WritableRepositoryInterface $repo, PackageInterface $package)
+    public function uninstall(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         throw new \InvalidArgumentException("not supported");
     }