diff --git a/apps/files_external/lib/Command/Import.php b/apps/files_external/lib/Command/Import.php
index 534c0a2d9d867..a4976b21cb7b3 100644
--- a/apps/files_external/lib/Command/Import.php
+++ b/apps/files_external/lib/Command/Import.php
@@ -181,7 +181,7 @@ private function getBackendByClass(string $className) {
 		}
 	}
 
-	protected function getStorageService($userId): StoragesService {
+	protected function getStorageService(string $userId): StoragesService {
 		if (empty($userId)) {
 			return $this->globalService;
 		}
diff --git a/apps/files_external/lib/Command/ListCommand.php b/apps/files_external/lib/Command/ListCommand.php
index 929e9d4f5151c..e4a33a99a922d 100644
--- a/apps/files_external/lib/Command/ListCommand.php
+++ b/apps/files_external/lib/Command/ListCommand.php
@@ -242,7 +242,7 @@ public function listMounts($userId, array $mounts, InputInterface $input, Output
 		}
 	}
 
-	protected function getStorageService($userId): StoragesService {
+	protected function getStorageService(string $userId): StoragesService {
 		if (empty($userId)) {
 			return $this->globalService;
 		}