diff --git a/graph/memstore/all_iterator.go b/graph/memstore/all_iterator.go
index 26cb643..abfc105 100644
--- a/graph/memstore/all_iterator.go
+++ b/graph/memstore/all_iterator.go
@@ -52,6 +52,10 @@ func (it *nodesAllIterator) Next() bool {
 	return true
 }
 
+func (it *nodesAllIterator) Err() error {
+	return nil
+}
+
 func newQuadsAllIterator(qs *QuadStore) *quadsAllIterator {
 	var out quadsAllIterator
 	out.Int64 = *iterator.NewInt64(1, qs.nextQuadID-1)
diff --git a/graph/memstore/iterator.go b/graph/memstore/iterator.go
index d93ba62..96911af 100644
--- a/graph/memstore/iterator.go
+++ b/graph/memstore/iterator.go
@@ -30,6 +30,7 @@ type Iterator struct {
 	iter   *b.Enumerator
 	data   string
 	result graph.Value
+	err    error
 }
 
 func cmp(a, b int64) int {
@@ -118,6 +119,7 @@ func (it *Iterator) Next() bool {
 	}
 	result, _, err := it.iter.Next()
 	if err != nil {
+		it.err = err
 		return graph.NextLogOut(it, nil, false)
 	}
 	if !it.checkValid(result) {
@@ -127,6 +129,10 @@ func (it *Iterator) Next() bool {
 	return graph.NextLogOut(it, it.result, true)
 }
 
+func (it *Iterator) Err() error {
+	return it.err
+}
+
 func (it *Iterator) ResultTree() *graph.ResultTree {
 	return graph.NewResultTree(it.Result())
 }