diff --git a/model/content-store/ccnx-content-store.cc b/model/content-store/ccnx-content-store.cc
index ccbf200..abbf9c3 100644
--- a/model/content-store/ccnx-content-store.cc
+++ b/model/content-store/ccnx-content-store.cc
@@ -58,7 +58,7 @@
 
 //////////////////////////////////////////////////////////////////////
 
-CcnxContentStoreEntry::CcnxContentStoreEntry (Ptr<CcnxContentObjectHeader> header, Ptr<const Packet> packet)
+CcnxContentStoreEntry::CcnxContentStoreEntry (Ptr<const CcnxContentObjectHeader> header, Ptr<const Packet> packet)
   : m_header (header)
   , m_packet (packet->Copy ())
 {