diff --git a/src/Composer/ExtensionLoader.php b/src/Composer/ExtensionLoader.php
index <HASH>..<HASH> 100644
--- a/src/Composer/ExtensionLoader.php
+++ b/src/Composer/ExtensionLoader.php
@@ -18,7 +18,7 @@ class ExtensionLoader
     /** @var ResolvedExtension[] */
     protected $extensions = [];
     /** @var string[] */
-    protected $map;
+    protected $map = [];
 
     /** @var FilesystemInterface */
     private $filesystem;
@@ -102,6 +102,16 @@ class ExtensionLoader
     }
 
     /**
+     * Return the in-use extension name map.
+     *
+     * @return string[]
+     */
+    public function getMap()
+    {
+        return $this->map;
+    }
+
+    /**
      * Resolve a Composer or PHP extension name to the stored key.
      *
      * @param $name
Getter for the in-use extension name map