diff --git a/product/ZSQLCatalog/SQLCatalog.py b/product/ZSQLCatalog/SQLCatalog.py
index ae73a328291c10bda16d332903852c67c66b3e08..edba3fe69b95414428a701da9381f313899bdae0 100755
--- a/product/ZSQLCatalog/SQLCatalog.py
+++ b/product/ZSQLCatalog/SQLCatalog.py
@@ -39,6 +39,7 @@ from xml.dom.minidom import parse, parseString, getDOMImplementation
 from xml.sax.saxutils import escape, quoteattr
 import os
 import md5
+import threading
 
 try:
   from Products.PageTemplates.Expressions import SecureModuleImporter