1 files changed, 3 insertions, 4 deletions

diff --git a/src/alloc.c b/src/alloc.c
index dd4823bd9e3..c38376d80bc 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -4979,10 +4979,9 @@ mark_object (arg)
       if (XMISCTYPE (obj) == Lisp_Misc_Free)
         {
           /* This is (probably) a freed marker which may still exist on
-             a buffer undo list, so accept it here.  */
-          /* If we reuse the marker, and it still exists on the undo
-             list, and we do undo, behaviour is unpredictable --
-             but at least we don't crash here.  KFS 2004-05-17 */
+             a buffer undo list, so accept it here, as check below will
+             fail (not live).  KFS 2004-05-17 */
+          XMARKER (obj)->gcmarkbit = 1;
           break;
         }
       CHECK_ALLOCATED_AND_LIVE (live_misc_p);