diff --git a/src/Handler.php b/src/Handler.php
index bf98640a5526f0f4b64465e61d8e9a88dde543b9..13e9eb85bb652f68dab9da8e4f80ae1791e1fb6e 100644
--- a/src/Handler.php
+++ b/src/Handler.php
@@ -61,6 +61,11 @@ class Handler {
     $content = array_merge_recursive($content, $options);
     $jsonFile = new JsonFile($projectRoot . '/composer.json');
     $jsonFile->write($content);
+
+    // Add some patterns to .gitignore.
+    foreach (['/vendor/', '/web/', '.env'] as $item) {
+      exec('git ignore ' . $item);
+    }
   }
 
   /**