diff --git a/src/mon/OSDMonitor.cc b/src/mon/OSDMonitor.cc
index 64430dc552933..d7aa48b03dc38 100644
--- a/src/mon/OSDMonitor.cc
+++ b/src/mon/OSDMonitor.cc
@@ -2542,16 +2542,22 @@ class C_AckMarkedDown : public C_MonOp {
     MonOpRequestRef op)
     : C_MonOp(op), osdmon(osdmon) {}
 
-  void _finish(int) override {
-    MOSDMarkMeDown *m = static_cast<MOSDMarkMeDown*>(op->get_req());
-    osdmon->mon->send_reply(
-      op,
-      new MOSDMarkMeDown(
-	m->fsid,
-	m->target_osd,
-	m->target_addrs,
-	m->get_epoch(),
-	false));   // ACK itself does not request an ack
+  void _finish(int r) override {
+    if (r == 0) {
+      MOSDMarkMeDown *m = static_cast<MOSDMarkMeDown*>(op->get_req());
+      osdmon->mon->send_reply(
+        op,
+        new MOSDMarkMeDown(
+          m->fsid,
+          m->target_osd,
+          m->target_addrs,
+          m->get_epoch(),
+          false));   // ACK itself does not request an ack
+    } else if (r == -EAGAIN) {
+        osdmon->dispatch(op);
+    } else {
+        ceph_abort_msgf("C_AckMarkedDown: unknown result %d", r);
+    }
   }
   ~C_AckMarkedDown() override {
   }