diff --git a/mongo/collection.go b/mongo/collection.go
index 4b1a855f409ed828f6d47f69d415fbc0fcbb8ace..93108fd0b1b3ab5d7a19e73c1ee952be41cee9cc 100644
--- a/mongo/collection.go
+++ b/mongo/collection.go
@@ -30,7 +30,6 @@ import (
 	"labix.org/v2/mgo"
 	"labix.org/v2/mgo/bson"
 	"upper.io/db"
-	"upper.io/db/util"
 )
 
 // Mongodb Collection
@@ -38,7 +37,6 @@ type Collection struct {
 	name       string
 	parent     *Source
 	collection *mgo.Collection
-	util.C
 }
 
 type chunks struct {
diff --git a/mongo/database.go b/mongo/database.go
index e6914f58d9ba2dc12dda91c2904582ace8101c2b..8a54337c72420f70d679a0c421c9d40da5dc57af 100644
--- a/mongo/database.go
+++ b/mongo/database.go
@@ -203,8 +203,6 @@ func (self *Source) Collection(names ...string) (db.Collection, error) {
 	col.parent = self
 	col.collection = self.database.C(name)
 
-	col.DB = self
-
 	if col.Exists() == false {
 		err = db.ErrCollectionDoesNotExist
 	}