diff --git a/graphx/src/main/scala/org/apache/spark/graphx/Pregel.scala b/graphx/src/main/scala/org/apache/spark/graphx/Pregel.scala
index 4572eab2875bb..5e55620147df8 100644
--- a/graphx/src/main/scala/org/apache/spark/graphx/Pregel.scala
+++ b/graphx/src/main/scala/org/apache/spark/graphx/Pregel.scala
@@ -150,6 +150,7 @@ object Pregel extends Logging {
       oldMessages.unpersist(blocking=false)
       newVerts.unpersist(blocking=false)
       prevG.unpersistVertices(blocking=false)
+      prevG.edges.unpersist(blocking=false)
       // count the iteration
       i += 1
     }