diff --git a/graph/src/main/scala/org/apache/spark/graph/GraphLab.scala b/graph/src/main/scala/org/apache/spark/graph/GraphLab.scala
index 799c0fc901..aa35f9a746 100644
--- a/graph/src/main/scala/org/apache/spark/graph/GraphLab.scala
+++ b/graph/src/main/scala/org/apache/spark/graph/GraphLab.scala
@@ -89,9 +89,9 @@ object GraphLab {
     }
 
     // Used to set the active status of vertices for the next round
-    def applyActive(vid: Vid, data: (Boolean, VD), newActive: Boolean): (Boolean, VD) = {
+    def applyActive(vid: Vid, data: (Boolean, VD), newActiveOpt: Option[Boolean]): (Boolean, VD) = {
       val (prevActive, vData) = data
-      (newActive, vData)
+      (newActiveOpt.getOrElse(false), vData)
     }
 
     // Main Loop ---------------------------------------------------------------------
@@ -113,7 +113,7 @@ object GraphLab {
       val scattered: RDD[(Vid, Boolean)] =
         activeGraph.aggregateNeighbors(scatter, _ || _, scatterDirection.reverse)
 
-      activeGraph = activeGraph.joinVertices(scattered)(applyActive).cache()
+      activeGraph = activeGraph.outerJoinVertices(scattered)(applyActive).cache()
 
       // Calculate the number of active vertices
       numActive = activeGraph.vertices.map{