diff --git a/BackupCommand.php b/BackupCommand.php
index 8db1949..040fe94 100644
--- a/BackupCommand.php
+++ b/BackupCommand.php
@@ -31,7 +31,7 @@ class BackupCommand extends Command
     /**
      *
      */
-    protected function configure()
+    protected function configure(): void
     {
         $this->setName('db:backup')
              ->addOption('data', 'd', InputArgument::OPTIONAL)