diff --git a/apps/files_encryption/lib/proxy.php b/apps/files_encryption/lib/proxy.php
index 126a593ee3cde7374477e20da48f441731b54125..b1af4676852e2de6285adf9a00eb77e7868fe12d 100644
--- a/apps/files_encryption/lib/proxy.php
+++ b/apps/files_encryption/lib/proxy.php
@@ -64,7 +64,10 @@ class Proxy extends \OC_FileProxy {
 
 		// we don't encrypt server-to-server shares
 		list($storage, ) = \OC\Files\Filesystem::resolvePath($path);
-		if ($storage instanceof OCA\Files_Sharing\External\Storage) {
+		/**
+		 * @var \OCP\Files\Storage $storage
+		 */
+		if ($storage->instanceOfStorage('OCA\Files_Sharing\External\Storage')) {
 			return true;
 		}