diff --git a/gc.c b/gc.c
index cec6c94334..a2b8589e4b 100644
--- a/gc.c
+++ b/gc.c
@@ -3139,11 +3139,13 @@ cvar_table_free_i(VALUE value, void *ctx)
     return ID_TABLE_CONTINUE;
 }
 
+#define ZOMBIE_OBJ_KEPT_FLAGS (FL_SEEN_OBJ_ID | FL_FINALIZE)
+
 static inline void
 make_zombie(rb_objspace_t *objspace, VALUE obj, void (*dfree)(void *), void *data)
 {
     struct RZombie *zombie = RZOMBIE(obj);
-    zombie->basic.flags = T_ZOMBIE | (zombie->basic.flags & (FL_SEEN_OBJ_ID | FL_FINALIZE));
+    zombie->basic.flags = T_ZOMBIE | (zombie->basic.flags & ZOMBIE_OBJ_KEPT_FLAGS);
     zombie->dfree = dfree;
     zombie->data = data;
     VALUE prev, next = heap_pages_deferred_final;
@@ -7587,7 +7589,7 @@ verify_internal_consistency_i(void *page_start, void *page_end, size_t stride,
         }
         else {
             if (BUILTIN_TYPE(obj) == T_ZOMBIE) {
-                GC_ASSERT((RBASIC(obj)->flags & ~FL_SEEN_OBJ_ID) == T_ZOMBIE);
+                GC_ASSERT((RBASIC(obj)->flags & ~ZOMBIE_OBJ_KEPT_FLAGS) == T_ZOMBIE);
                 data->zombie_object_count++;
             }
         }