diff --git a/env.go b/env.go
index 4737e09..c08bc70 100644
--- a/env.go
+++ b/env.go
@@ -54,7 +54,7 @@ func uniqueSymbols(a []Symbol) (ret []Symbol) {
 
 func exitFunc(_ ...Expression) (Expression, error) {
 	exit <- os.Interrupt
-	return NilObj, nil
+	return UndefObj, nil
 }
 
 func addFunc(args ...Expression) (Expression, error) {
diff --git a/repl.go b/repl.go
index dd2a999..6ae58e9 100644
--- a/repl.go
+++ b/repl.go
@@ -126,11 +126,13 @@ func (i *Interpreter) check() {
 }
 
 func (i *Interpreter) runInInteractiveMode() {
+	go i.checkExit()
 	i.printTips()
 	i.prompt.Run()
 }
 
 func (i *Interpreter) exitProcess() {
+	close(i.exit)
 	fmt.Println("\nExiting...")
 	os.Exit(0)
 }