diff -r bc8ab048b208 -r 9d08152b46a7 pvl/verkko/hosts.py
--- a/pvl/verkko/hosts.py	Mon Dec 17 19:17:47 2012 +0200
+++ b/pvl/verkko/hosts.py	Mon Dec 17 19:24:09 2012 +0200
@@ -246,11 +246,13 @@
         filters = {}
 
         for attr in self.HOST_ATTRS :
-            values = self.request.args.getlist(attr)
+            values = [value.strip() for value in self.request.args.getlist(attr) if value.strip()]
 
+            # ignore empty fields
             if not values :
                 continue
             
+            # build query expression
             filter = db.or_(*[self.filter_attr(attr, value) for value in values])
 
             log.debug("filter %s: %s", attr, filter)