diff --git a/engine/storage_mongo_datadb.go b/engine/storage_mongo_datadb.go
index 1879c3b1e..9d00c226c 100644
--- a/engine/storage_mongo_datadb.go
+++ b/engine/storage_mongo_datadb.go
@@ -125,7 +125,7 @@ func NewMongoStorage(host, port, db, user, pass string, cdrsIndexes []string) (*
 	}
 
 	ndb := session.DB(db)
-	session.SetMode(mgo.Monotonic, true)
+	session.SetMode(mgo.Strong, true)
 	index := mgo.Index{
 		Key:        []string{"key"},
 		Unique:     true,  // Prevent two documents from having the same index key