diff --git a/src/ConfiguredMediator.php b/src/ConfiguredMediator.php
index 37b42d1..e8819e3 100644
--- a/src/ConfiguredMediator.php
+++ b/src/ConfiguredMediator.php
@@ -34,8 +34,7 @@ abstract protected function getDistributorConfig(): string;
 
     public function uninstall(Composer $composer, IOInterface $io)
     {
-        $this->composer = $composer;
-        $this->io       = $io;
+        parent::uninstall($composer, $io);
         $this->removePhars();
     }
 
@@ -45,7 +44,7 @@ public function installOrUpdateFunction(PackageEvent $event): void
         // we do not want to crash if no GnuPG was found
         // but display a noticeable warning to the user
         if ($gnuPG === null) {
-            $this->io->write(
+            $this->getIO()->write(
                 PHP_EOL .
                 '    <warning>WARNING</warning>' . PHP_EOL .
                 '    No GPG installation found! Use installed PHARs with care. ' . PHP_EOL .
@@ -77,7 +76,7 @@ private function createInstallerFromConfig(Config $config, PackageEvent $event):
     {
         return new Installer(
             $config->package(),
-            $this->io,
+            $this->getIO(),
             $event
         );
     }
@@ -99,7 +98,7 @@ private function createKeyDirectory(Config $config): KeyDirectory
 
     private function removePhars(): void
     {
-        $binDir = $this->composer->getConfig()->get('bin-dir');
+        $binDir = $this->getComposer()->getConfig()->get('bin-dir');
 
         foreach ($this->config->phars()->getList() as $phar) {
             $this->deleteFile($phar, $binDir);
@@ -112,12 +111,12 @@ private function deleteFile(File $phar, string $binDir): void
 
         if (is_file($pharLocation)) {
             if (!is_writable($pharLocation)) {
-                $this->io->write(
+                $this->getIO()->write(
                     sprintf('  - Can not remove phar \'%1$s\' (insufficient permissions)', $phar->pharName())
                 );
                 return;
             }
-            $this->io->write(sprintf('  - Removing phar <info>%1$s</info>', $phar->pharName()));
+            $this->getIO()->write(sprintf('  - Removing phar <info>%1$s</info>', $phar->pharName()));
             unlink($pharLocation);
         }
     }
diff --git a/src/PluginBase.php b/src/PluginBase.php
index 65d41a8..05bd366 100644
--- a/src/PluginBase.php
+++ b/src/PluginBase.php
@@ -15,10 +15,12 @@
 abstract class PluginBase implements PluginInterface, EventSubscriberInterface
 {
     /** @var \Composer\Composer */
-    protected $composer;
+    private $composer;
 
     /** @var \Composer\IO\IOInterface */
-    protected $io;
+    private $io;
+
+    abstract public function installOrUpdateFunction(PackageEvent $event) : void;
 
     public function activate(Composer $composer, IOInterface $io)
     {
@@ -59,5 +61,19 @@ public function createInstaller(string $pluginName, PackageEvent $event) : Insta
         );
     }
 
-    abstract public function installOrUpdateFunction(PackageEvent $event) : void;
+    protected function getIO(): IOInterface
+    {
+        if (!$this->io) {
+            throw new \RuntimeException('IO not set');
+        }
+        return $this->io;
+    }
+
+    protected function getComposer(): Composer
+    {
+        if (!$this->composer) {
+            throw new \RuntimeException('Composer not set');
+        }
+        return $this->composer;
+    }
 }