diff --git a/src/file.php b/src/file.php
index c5c30a4..5ddc3b1 100644
--- a/src/file.php
+++ b/src/file.php
@@ -29,7 +29,7 @@ class file {
     return $file;
   }
   
-  static function writer($output, ?string $mode=null, ?callable $func=null): FileWriter {
+  static function writer($output, ?string $mode="w+b", ?callable $func=null): FileWriter {
     $file = new FileWriter(self::fix_dash($output), $mode);
     if ($func !== null) {
       try {