diff --git a/src/calibre/srv/legacy.py b/src/calibre/srv/legacy.py
index d05fb696a5..6c5aa803c9 100644
--- a/src/calibre/srv/legacy.py
+++ b/src/calibre/srv/legacy.py
@@ -256,7 +256,7 @@ def browse(ctx, rd, rest):
     if rest.startswith('book/'):
         # implementation of https://bugs.launchpad.net/calibre/+bug/1698411
         # redirect old server book URLs to new URLs
-        redirect = ctx.url_for(None) + '#book_id=' + rest[5:] + "&panel=book_details"
+        redirect = ctx.url_for(None) + '#book_id=' + int(rest[5:]) + "&panel=book_details"
         from lxml import etree as ET
         return html(ctx, rd, endpoint,
                  E.html(E.head(