diff --git a/archivebox/index/schema.py b/archivebox/index/schema.py
index dd8fe7cd..68d840a2 100644
--- a/archivebox/index/schema.py
+++ b/archivebox/index/schema.py
@@ -249,7 +249,7 @@ class Link:
     @property
     def link_dir(self) -> str:
         from ..config import CONFIG
-        return Path(CONFIG['ARCHIVE_DIR']) / self.timestamp
+        return str(Path(CONFIG['ARCHIVE_DIR']) / self.timestamp)
 
     @property
     def archive_path(self) -> str: