diff --git a/lib/Command/Rename.php b/lib/Command/Rename.php
index bbe578fd9..fe5abdc56 100644
--- a/lib/Command/Rename.php
+++ b/lib/Command/Rename.php
@@ -28,7 +28,7 @@
 use Symfony\Component\Console\Output\OutputInterface;
 
 class Rename extends FolderCommand {
-	protected function configure() {
+	protected function configure(): void {
 		$this
 			->setName('groupfolders:rename')
 			->setDescription('Rename group folder')
@@ -37,7 +37,7 @@ protected function configure() {
 		parent::configure();
 	}
 
-	protected function execute(InputInterface $input, OutputInterface $output) {
+	protected function execute(InputInterface $input, OutputInterface $output): int {
 		$folder = $this->getFolder($input, $output);
 		if ($folder === false) {
 			return -1;