diff --git a/src/Patches.php b/src/Patches.php
index 52e4203a..3d7d864a 100644
--- a/src/Patches.php
+++ b/src/Patches.php
@@ -48,6 +48,11 @@ class Patches implements PluginInterface, EventSubscriberInterface {
    */
   protected $patches;
 
+  /**
+   * @var array $installedPatches
+   */
+  protected $installedPatches;
+
   /**
    * Apply plugin modifications to composer
    *