diff --git a/core/api/src/main/java/org/onlab/onos/net/flow/DefaultTrafficSelector.java b/core/api/src/main/java/org/onlab/onos/net/flow/DefaultTrafficSelector.java
index a388b48..f51d75e 100644
--- a/core/api/src/main/java/org/onlab/onos/net/flow/DefaultTrafficSelector.java
+++ b/core/api/src/main/java/org/onlab/onos/net/flow/DefaultTrafficSelector.java
@@ -8,7 +8,6 @@
 import org.onlab.packet.MacAddress;
 import org.onlab.packet.VlanId;
 
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
@@ -27,7 +26,7 @@
      * @param criteria criteria
      */
     private DefaultTrafficSelector(Set<Criterion> criteria) {
-        this.criteria = Collections.unmodifiableSet(criteria);
+        this.criteria = ImmutableSet.copyOf(criteria);
     }
 
     @Override
diff --git a/core/api/src/main/java/org/onlab/onos/net/flow/DefaultTrafficTreatment.java b/core/api/src/main/java/org/onlab/onos/net/flow/DefaultTrafficTreatment.java
index 269347a..d202217 100644
--- a/core/api/src/main/java/org/onlab/onos/net/flow/DefaultTrafficTreatment.java
+++ b/core/api/src/main/java/org/onlab/onos/net/flow/DefaultTrafficTreatment.java
@@ -7,7 +7,8 @@
 import org.onlab.packet.MacAddress;
 import org.onlab.packet.VlanId;
 
-import java.util.Collections;
+import com.google.common.collect.ImmutableList;
+
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Objects;
@@ -25,7 +26,7 @@
      * @param instructions treatment instructions
      */
     private DefaultTrafficTreatment(List<Instruction> instructions) {
-        this.instructions = Collections.unmodifiableList(instructions);
+        this.instructions = ImmutableList.copyOf(instructions);
     }
 
     @Override