diff --git a/racket/src/racket/gc2/weak.c b/racket/src/racket/gc2/weak.c
index 94e9df4886..f6954989a9 100644
--- a/racket/src/racket/gc2/weak.c
+++ b/racket/src/racket/gc2/weak.c
@@ -313,6 +313,8 @@ static int mark_ready_ephemerons(GCTYPE *gc)
   GC_Ephemeron *waiting = NULL, *next, *eph;
   int did_one = 0;
 
+  GC_mark_no_recur(gc, 1);
+
   for (eph = gc->ephemerons; eph; eph = next) {
     next = eph->next;
     if (is_marked(gc, eph->key)) {
@@ -326,6 +328,8 @@ static int mark_ready_ephemerons(GCTYPE *gc)
   }
   gc->ephemerons = waiting;
 
+  GC_mark_no_recur(gc, 0);
+
   return did_one;
 }