diff --git a/core/src/main/scala/org/apache/spark/rpc/RpcEnv.scala b/core/src/main/scala/org/apache/spark/rpc/RpcEnv.scala
index 26c198380c2ab..1709bdf560b6f 100644
--- a/core/src/main/scala/org/apache/spark/rpc/RpcEnv.scala
+++ b/core/src/main/scala/org/apache/spark/rpc/RpcEnv.scala
@@ -201,7 +201,8 @@ private[rpc] class RpcTimeoutException(message: String, cause: TimeoutException)
  * @param duration timeout duration in seconds
  * @param timeoutProp the configuration property that controls this timeout
  */
-private[spark] class RpcTimeout(val duration: FiniteDuration, val timeoutProp: String) {
+private[spark] class RpcTimeout(val duration: FiniteDuration, val timeoutProp: String)
+  extends Serializable {
 
   /** Amends the standard message of TimeoutException to include the description */
   private def createRpcTimeoutException(te: TimeoutException): RpcTimeoutException = {