diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index d2cdc8ee3155..24acdd580e79 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -114,7 +114,7 @@ static struct ceph_monmap *ceph_monmap_decode(void **p, void *end, bool msgr2)
 
 	dout("%s fsid %pU epoch %u num_mon %u\n", __func__, &fsid, epoch,
 	     num_mon);
-	if (num_mon > CEPH_MAX_MON)
+	if (num_mon == 0 || num_mon > CEPH_MAX_MON)
 		goto e_inval;
 
 	monmap = kmalloc_flex(*monmap, mon_inst, num_mon, GFP_NOIO);