diff --git a/saul-core/src/main/scala/edu/illinois/cs/cogcomp/saul/datamodel/node/Node.scala b/saul-core/src/main/scala/edu/illinois/cs/cogcomp/saul/datamodel/node/Node.scala
index 22e244be..09fd3059 100644
--- a/saul-core/src/main/scala/edu/illinois/cs/cogcomp/saul/datamodel/node/Node.scala
+++ b/saul-core/src/main/scala/edu/illinois/cs/cogcomp/saul/datamodel/node/Node.scala
@@ -66,9 +66,9 @@ class Node[T <: AnyRef](
 
   def filterNode(property: DiscreteProperty[T], value: String): Node[T] = {
     val node = new Node[T](this.keyFunc, this.tag)
-    node populate collection.filter {
-      nt => property.sensor(nt.apply) == value
-    }.toSeq.map(_.apply)
+    node populate collection.collect {
+      case nt if property.sensor(nt.apply) == value => nt.apply
+    }
     node
   }
 
@@ -303,7 +303,7 @@ class JoinNode[A <: AnyRef, B <: AnyRef](val na: Node[A], val nb: Node[B], match
 
   private def matchAndAddChildrenA(a: A, train: Boolean = true, populateEdge: Boolean = true): Unit = {
     val instances = if (train) nb.getTrainingInstances else nb.getTestingInstances
-    for ((a, b) <- instances.filter(matcher(a, _)).map(a -> _)) {
+    for ((a, b) <- instances.collect { case b if matcher(a, b) => a -> b }) {
       if (!contains(a -> b))
         this addInstance (a -> b, train, populateEdge)
     }
@@ -311,7 +311,7 @@ class JoinNode[A <: AnyRef, B <: AnyRef](val na: Node[A], val nb: Node[B], match
 
   private def matchAndAddChildrenB(b: B, train: Boolean = true, populateEdge: Boolean = true): Unit = {
     val instances = if (train) na.getTrainingInstances else na.getTestingInstances
-    for ((a, b) <- instances.filter(matcher(_, b)).map(_ -> b)) {
+    for ((a, b) <- instances.collect { case a if matcher(a, b) => a -> b }) {
       if (!contains(a -> b))
         this addInstance (a -> b, train, populateEdge)
     }