diff --git a/src/calibre/library/server/browse.py b/src/calibre/library/server/browse.py
index 463fcd6fde..142f40efab 100644
--- a/src/calibre/library/server/browse.py
+++ b/src/calibre/library/server/browse.py
@@ -509,7 +509,7 @@ class BrowseServer(object):
 
         hide_sort = 'true' if dt == 'series' else 'false'
         if category == 'search':
-            which = unhexlify(cid)
+            which = unhexlify(cid).decode('utf-8')
             try:
                 ids = self.search_cache('search:"%s"'%which)
             except: