Index: tol/PackArchive/PackArchive.cpp
===================================================================
--- tol/PackArchive/PackArchive.cpp	(revision 94e9139af92af3c3c6f6378d3ebcd84c8597620c)
+++ tol/PackArchive/PackArchive.cpp	(revision afbee11aa92df1e1421b26cc25fdf5c04528db9a)
@@ -78,5 +78,5 @@
 { 
   if(_isInitialized) { return(false); }
-  SetEmptyKey  (_instances, NULL);
+  SetEmptyKey  (_instances, 0);
   SetDeletedKey(_instances, -1);
   return(true);