diff --git a/conway.go b/conway.go
index 2c5c05a..816db99 100644
--- a/conway.go
+++ b/conway.go
@@ -59,17 +59,16 @@ func initGrid(width, height int, parent ...[][]Cell) ([][]Cell, error) {
 	return cells, nil
 }
 
-const FPS = 10
-
 var grid [][]Cell
 
-func setup(callback func([][]Cell), width, height int) {
+func setup(callback func([][]Cell), width, height, FPS int) chan bool {
 	grid, _ = initGrid(width, height)
 
-	// Prepare
-	ticker := time.NewTicker(time.Second / FPS)
+	// Prepare ticker and finishing flag
+	ticker := time.NewTicker(time.Second / time.Duration(FPS))
 	done := make(chan bool)
 
+	// Run game loop
 	go func() {
 		for {
 			select {
@@ -80,6 +79,9 @@ func setup(callback func([][]Cell), width, height int) {
 			}
 		}
 	}()
+
+	// Return flag to be stopped outside
+	return done
 }
 
 func draw(callback func([][]Cell)) {