diff --git a/apps/files_external/lib/Command/Import.php b/apps/files_external/lib/Command/Import.php
index 534c0a2d9d8..a4976b21cb7 100644
--- a/apps/files_external/lib/Command/Import.php
+++ b/apps/files_external/lib/Command/Import.php
@@ -181,7 +181,7 @@ class Import extends Base {
 		}
 	}
 
-	protected function getStorageService($userId): StoragesService {
+	protected function getStorageService(string $userId): StoragesService {
 		if (empty($userId)) {
 			return $this->globalService;
 		}
diff --git a/apps/files_external/lib/Command/ListCommand.php b/apps/files_external/lib/Command/ListCommand.php
index 929e9d4f515..e4a33a99a92 100644
--- a/apps/files_external/lib/Command/ListCommand.php
+++ b/apps/files_external/lib/Command/ListCommand.php
@@ -242,7 +242,7 @@ class ListCommand extends Base {
 		}
 	}
 
-	protected function getStorageService($userId): StoragesService {
+	protected function getStorageService(string $userId): StoragesService {
 		if (empty($userId)) {
 			return $this->globalService;
 		}