diff --git a/src/Ftp/FtpAdapter.php b/src/Ftp/FtpAdapter.php
index d44e4b2ce..4b63d4eab 100644
--- a/src/Ftp/FtpAdapter.php
+++ b/src/Ftp/FtpAdapter.php
@@ -611,7 +611,7 @@ private function ensureDirectoryExists(string $dirname, ?string $visibility): vo
             if ($mode !== false && @ftp_chmod($connection, $mode, $location) === false) {
                 throw UnableToCreateDirectory::atLocation(
                     $dirPath,
-                    'unable to chmod the directory: ' . error_get_last()['message'] ?? 'reason unknown'
+                    'unable to chmod the directory: ' . (error_get_last()['message'] ?? 'reason unknown'),
                 );
             }
         }