diff --git a/core/api/src/main/java/org/onlab/onos/net/flow/TrafficSelector.java b/core/api/src/main/java/org/onlab/onos/net/flow/TrafficSelector.java
index c024e9c..9678dc1 100644
--- a/core/api/src/main/java/org/onlab/onos/net/flow/TrafficSelector.java
+++ b/core/api/src/main/java/org/onlab/onos/net/flow/TrafficSelector.java
@@ -24,8 +24,9 @@
          * already been added, it will be replaced by this one.
          *
          * @param criterion new criterion
+         * @return self
          */
-        void add(Criterion criterion);
+        Builder add(Criterion criterion);
 
         /**
          * Builds an immutable traffic selector.