diff --git a/openid-connect-common/src/main/java/org/mitre/openid/connect/model/UserInfo.java b/openid-connect-common/src/main/java/org/mitre/openid/connect/model/UserInfo.java
index ce18a5303..ac87a1537 100644
--- a/openid-connect-common/src/main/java/org/mitre/openid/connect/model/UserInfo.java
+++ b/openid-connect-common/src/main/java/org/mitre/openid/connect/model/UserInfo.java
@@ -16,10 +16,12 @@
  ******************************************************************************/
 package org.mitre.openid.connect.model;
 
+import java.io.Serializable;
+
 import com.google.gson.JsonObject;
 
 
-public interface UserInfo {
+public interface UserInfo extends Serializable {
 
 	/**
 	 * @return the userId