1 files changed, 1 insertions, 1 deletions

diff --git a/application/bookmark/BookmarkFileService.php b/application/bookmark/BookmarkFileService.php
index 804b2520..eb7899bf 100644
--- a/application/bookmark/BookmarkFileService.php
+++ b/application/bookmark/BookmarkFileService.php
@@ -349,7 +349,7 @@ class BookmarkFileService implements BookmarkServiceInterface
         $bookmarkDays = array_keys($bookmarkDays);
         sort($bookmarkDays);
 
-        return $bookmarkDays;
+        return array_map('strval', $bookmarkDays);
     }
 
     /**