diff --git a/tomo.go b/tomo.go
index 7920ac7..807da04 100644
--- a/tomo.go
+++ b/tomo.go
@@ -35,7 +35,7 @@ func Stop () {
 	backend = nil
 }
 
-func NewWindow (bounds image.Rectangle) MainWindow {
+func NewWindow (bounds image.Rectangle) (MainWindow, error) {
 	assertBackend()
 	return backend.NewWindow(bounds)
 }