diff --git a/src/main/java/javax/security/enterprise/CallerPrincipal.java b/src/main/java/javax/security/enterprise/CallerPrincipal.java
index b33052c..57936ff 100644
--- a/src/main/java/javax/security/enterprise/CallerPrincipal.java
+++ b/src/main/java/javax/security/enterprise/CallerPrincipal.java
@@ -16,13 +16,16 @@
 
 package javax.security.enterprise;
 
+import java.io.Serializable;
 import java.security.Principal;
 
 /**
  * Principal that represents the caller principal associated with the invocation being
  * processed by the container (e.g. the current HTTP request).
  */
-public class CallerPrincipal implements Principal {
+public class CallerPrincipal implements Principal, Serializable {
+
+    private static final long serialVersionUID = -6951555039431667786L;
 
     private final String name;