diff --git a/core/api/src/main/java/org/onlab/onos/net/host/HostClockService.java b/core/api/src/main/java/org/onlab/onos/net/host/HostClockService.java
index 49ef8f7..21de7a6 100644
--- a/core/api/src/main/java/org/onlab/onos/net/host/HostClockService.java
+++ b/core/api/src/main/java/org/onlab/onos/net/host/HostClockService.java
@@ -1,7 +1,7 @@
 package org.onlab.onos.net.host;
 
+import org.onlab.onos.net.HostId;
 import org.onlab.onos.store.Timestamp;
-import org.onlab.packet.MacAddress;
 
 /**
  * Interface for a logical clock service that issues per host timestamps.
@@ -9,9 +9,9 @@
 public interface HostClockService {
 
     /**
-     * Returns a new timestamp for the specified host mac address.
-     * @param hostMac host MAC address.
+     * Returns a new timestamp for the specified host.
+     * @param hostId identifier for the host.
      * @return timestamp.
      */
-    public Timestamp getTimestamp(MacAddress hostMac);
+    public Timestamp getTimestamp(HostId hostId);
 }
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/HostClockManager.java b/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/HostClockManager.java
index 49eeb06..176f05d 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/HostClockManager.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/HostClockManager.java
@@ -6,10 +6,10 @@
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Service;
+import org.onlab.onos.net.HostId;
 import org.onlab.onos.net.host.HostClockService;
 import org.onlab.onos.store.Timestamp;
 import org.onlab.onos.store.impl.WallClockTimestamp;
-import org.onlab.packet.MacAddress;
 import org.slf4j.Logger;
 
 /**
@@ -32,7 +32,7 @@
     }
 
     @Override
-    public Timestamp getTimestamp(MacAddress hostMac) {
+    public Timestamp getTimestamp(HostId hostId) {
         return new WallClockTimestamp();
     }
 }
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/serializers/DistributedStoreSerializers.java b/core/store/dist/src/main/java/org/onlab/onos/store/serializers/DistributedStoreSerializers.java
index c410103..a04539b 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/serializers/DistributedStoreSerializers.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/serializers/DistributedStoreSerializers.java
@@ -2,6 +2,7 @@
 
 import org.onlab.onos.store.common.impl.Timestamped;
 import org.onlab.onos.store.impl.MastershipBasedTimestamp;
+import org.onlab.onos.store.impl.WallClockTimestamp;
 import org.onlab.util.KryoPool;
 
 public final class DistributedStoreSerializers {
@@ -13,6 +14,7 @@
             .register(KryoPoolUtil.API)
             .register(Timestamped.class)
             .register(MastershipBasedTimestamp.class, new MastershipBasedTimestampSerializer())
+            .register(WallClockTimestamp.class)
             .build();
 
     // avoid instantiation