diff --git a/gc.c b/gc.c
index 7c652aaa1d..a12a3fa70f 100644
--- a/gc.c
+++ b/gc.c
@@ -8260,7 +8260,9 @@ gc_compact(rb_objspace_t *objspace, int use_toward_empty, int use_double_pages,
         /* pin objects referenced by maybe pointers */
         rb_gc();
         /* compact */
+        during_gc = TRUE;
         gc_compact_after_gc(objspace, use_toward_empty, use_double_pages, TRUE);
+        during_gc = FALSE;
     }
     objspace->flags.during_compacting = FALSE;
     return gc_compact_stats(objspace);