diff --git a/engine/lists.c b/engine/lists.c
index e982719..44b3785 100644
--- a/engine/lists.c
+++ b/engine/lists.c
@@ -107,7 +107,7 @@ LIST * list_new( OBJECT * value )
 {
     LIST * const head = list_alloc( 1 ) ;
     head->impl.size = 1;
-    list_begin( head )[ 0 ] = value;
+    list_begin( head )[ 0 ] = object_copy( value );
     return head;
 }
 
@@ -136,7 +136,7 @@ LIST * list_push_back( LIST * head, OBJECT * value )
         head = l;
     }
 
-    list_begin( head )[ size ] = value;
+    list_begin( head )[ size ] = object_copy( value );
     head->impl.size = size + 1;
 
     return head;