diff --git a/lib/net/hostlist.js b/lib/net/hostlist.js
index e380ae07..9b5906c0 100644
--- a/lib/net/hostlist.js
+++ b/lib/net/hostlist.js
@@ -303,6 +303,8 @@ HostList.prototype.flush = co(function* flush() {
   if (!this.needsFlush)
     return;
 
+  this.needsFlush = false;
+
   this.logger.debug('Writing hosts to %s.', filename);
 
   json = this.toJSON();