diff --git a/confetti/confetti.go b/confetti/confetti.go
index b3aee21..faf3a9a 100644
--- a/confetti/confetti.go
+++ b/confetti/confetti.go
@@ -64,7 +64,10 @@ func InitialModel() model {
 	if err != nil {
 		panic(err)
 	}
+	return InitialModelWithSize(width, height)
+}
 
+func InitialModelWithSize(width, height int) model {
 	return model{system: &simulation.System{
 		Particles: Spawn(width, height),
 		Frame: simulation.Frame{
diff --git a/fireworks/fireworks.go b/fireworks/fireworks.go
index 715731c..3824221 100644
--- a/fireworks/fireworks.go
+++ b/fireworks/fireworks.go
@@ -65,7 +65,10 @@ func InitialModel() model {
 	if err != nil {
 		panic(err)
 	}
+	return InitialModelWithSize(width, height)
+}
 
+func InitialModelWithSize(width, height int) model {
 	return model{system: &simulation.System{
 		Particles: Spawn(width, height),
 		Frame: simulation.Frame{