diff --git a/src/or/nodelist.c b/src/or/nodelist.c
index 08131219b7..308aaa8658 100644
--- a/src/or/nodelist.c
+++ b/src/or/nodelist.c
@@ -317,6 +317,12 @@ nodelist_purge(void)
   for (iter = HT_START(nodelist_map, &the_nodelist->nodes_by_id); iter; ) {
     node_t *node = *iter;
 
+    if (node->md && !node->rs) {
+      /* An md is only useful if there is an rs. */
+      node->md->held_by_node = 0;
+      node->md = NULL;
+    }
+
     if (node_is_usable(node)) {
       iter = HT_NEXT(nodelist_map, &the_nodelist->nodes_by_id, iter);
     } else {