diff --git a/streaming/src/main/scala/org/apache/spark/streaming/dstream/ReducedWindowedDStream.scala b/streaming/src/main/scala/org/apache/spark/streaming/dstream/ReducedWindowedDStream.scala
index b334d68bf9910..40da31318942e 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/dstream/ReducedWindowedDStream.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/dstream/ReducedWindowedDStream.scala
@@ -43,7 +43,7 @@ class ReducedWindowedDStream[K: ClassTag, V: ClassTag](
   ) extends DStream[(K,V)](parent.ssc) {
 
   assert(_windowDuration.isMultipleOf(parent.slideDuration),
-    "The window duration of ReducedWindowedDStream (" + _slideDuration + ") " +
+    "The window duration of ReducedWindowedDStream (" + _windowDuration + ") " +
       "must be multiple of the slide duration of parent DStream (" + parent.slideDuration + ")"
   )