diff --git a/uutlGenerics.pas b/uutlGenerics.pas
index 71ba125..0e8f47b 100644
--- a/uutlGenerics.pas
+++ b/uutlGenerics.pas
@@ -1117,7 +1117,8 @@ end;
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 procedure TutlCustomMap.THashSet.DestroyItem(const aItem: PListItem; const aFreeItem: Boolean);
 begin
-  utlFreeOrFinalize(aItem^.data.key,   TypeInfo(aItem^.data.key),   aFreeItem and OwnsObjects);
+  // never free objects used as keys, but do finalize strings, interfaces etc.
+  utlFreeOrFinalize(aItem^.data.key,   TypeInfo(aItem^.data.key),   false);
   utlFreeOrFinalize(aItem^.data.value, TypeInfo(aItem^.data.value), aFreeItem and OwnsObjects);
   inherited DestroyItem(aItem, aFreeItem);
 end;