diff --git a/src/calibre/library/caches.py b/src/calibre/library/caches.py
index 191ac53f94..998c21c50c 100644
--- a/src/calibre/library/caches.py
+++ b/src/calibre/library/caches.py
@@ -20,6 +20,7 @@ from calibre.utils.localization import (canonicalize_lang, lang_map, get_udc,
 from calibre.ebooks.metadata import title_sort, author_to_author_sort
 from calibre.ebooks.metadata.opf2 import metadata_to_opf
 from calibre import prints
+from calibre.utils.icu import primary_find
 
 class MetadataBackup(Thread): # {{{
     '''
@@ -147,9 +148,10 @@ def _match(query, value, matchkind):
                             return True
                 elif query == t:
                     return True
-            elif ((matchkind == REGEXP_MATCH and re.search(query, t, re.I|re.UNICODE)) or ### search unanchored
-                  (matchkind == CONTAINS_MATCH and query in t)):
-                    return True
+            elif matchkind == REGEXP_MATCH:
+                return re.search(query, t, re.I|re.UNICODE)
+            elif matchkind == CONTAINS_MATCH:
+                return primary_find(query, t)[0] != -1
         except re.error:
             pass
     return False