diff --git a/src/main/java/net/onrc/onos/core/matchaction/action/OutputAction.java b/src/main/java/net/onrc/onos/core/matchaction/action/OutputAction.java
index 792b76e..2453640 100644
--- a/src/main/java/net/onrc/onos/core/matchaction/action/OutputAction.java
+++ b/src/main/java/net/onrc/onos/core/matchaction/action/OutputAction.java
@@ -49,4 +49,10 @@
         return Objects.equal(this.portNumber, that.portNumber);
     }
 
+    @Override
+    public String toString() {
+        return Objects.toStringHelper(getClass())
+                .add("portNumber", portNumber)
+                .toString();
+    }
 }