diff --git a/graphx/src/main/scala/org/apache/spark/graphx/GraphOps.scala b/graphx/src/main/scala/org/apache/spark/graphx/GraphOps.scala
index 02afaa987d40d19a67631f02aa17a4d49abf5d29..d0dd45dba618ee155995dae22964807abc132063 100644
--- a/graphx/src/main/scala/org/apache/spark/graphx/GraphOps.scala
+++ b/graphx/src/main/scala/org/apache/spark/graphx/GraphOps.scala
@@ -254,7 +254,7 @@ class GraphOps[VD: ClassTag, ED: ClassTag](graph: Graph[VD, ED]) extends Seriali
    * Picks a random vertex from the graph and returns its ID.
    */
   def pickRandomVertex(): VertexId = {
-    val probability = 50 / graph.numVertices
+    val probability = 50.0 / graph.numVertices
     var found = false
     var retVal: VertexId = null.asInstanceOf[VertexId]
     while (!found) {