diff --git a/core/src/main/scala/spark/broadcast/HttpBroadcast.scala b/core/src/main/scala/spark/broadcast/HttpBroadcast.scala
index e4b135644814b0dd38cb282ca3c261ba1e81f98a..aa8bb77f414f7b83d556ac6ef822ab83adf44a04 100644
--- a/core/src/main/scala/spark/broadcast/HttpBroadcast.scala
+++ b/core/src/main/scala/spark/broadcast/HttpBroadcast.scala
@@ -76,6 +76,7 @@ private object HttpBroadcast extends Logging {
   def stop() {
     if (server != null) {
       server.stop()
+      server = null
     }
   }