diff --git a/model/ccnx-content-store.h b/model/ccnx-content-store.h
index df92e1c..dd0f884 100644
--- a/model/ccnx-content-store.h
+++ b/model/ccnx-content-store.h
@@ -174,7 +174,7 @@
    * If an entry is found, it is promoted to the top of most recent
    * used entries index, \see m_contentStore
    */
-  boost::tuple<Ptr<Packet>, Ptr<CcnxContentObjectHeader> >
+  boost::tuple<Ptr<Packet>, Ptr<const CcnxContentObjectHeader> >
   Lookup (Ptr<const CcnxInterestHeader> interest);
             
   /**