diff --git a/layouts/flow.go b/layouts/flow.go
index 8baa762..3790dd3 100644
--- a/layouts/flow.go
+++ b/layouts/flow.go
@@ -43,7 +43,7 @@ func (flow Flow) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
 	for index < len(boxes) {
 		// get a slice of boxes for this major step
 		stepIndexEnd := index + minorSteps
-		if stepIndexEnd >= len(boxes) { stepIndexEnd = len(boxes) - 1 }
+		if stepIndexEnd > len(boxes) { stepIndexEnd = len(boxes) }
 		step := boxes[index:stepIndexEnd]
 		index += minorSteps