diff --git a/src/Update/migrations.php b/src/Update/migrations.php
index 6eefdc5..ff1ffba 100644
--- a/src/Update/migrations.php
+++ b/src/Update/migrations.php
@@ -272,3 +272,16 @@ function drupal_tools_update_13() : UpdateResult {
     'Removed direct dependency to ' . implode(', ', $remove),
   ]);
 }
+
+/**
+ * Allow phpstan/extension-installer. This was accidentally removed by drupal_tools_update_13.
+ */
+function drupal_tools_update_14() : UpdateResult {
+  // Ensure drupal/core-dev is required.
+  (new Process(['composer', 'config', 'allow-plugins.phpstan/extension-installer', 'true', '--no-interaction']))
+    ->run();
+
+  return new UpdateResult([
+    'Added phpstan/extension-installer to allow-plugins',
+  ]);
+}