diff --git a/cmd/add.go b/cmd/add.go
index 5ac2bdd..3791972 100644
--- a/cmd/add.go
+++ b/cmd/add.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 
@@ -22,7 +23,7 @@ func add(config *config) error {
 }
 
 func _add(filepath string, todo pttodo.Todo) error {
-	target := filepath + ".todo." + uuid.New().String()
+	target := fmt.Sprintf("%s.todo.%s", filepath, uuid.New().String())
 
 	c, err := yaml.Marshal([]pttodo.Todo{todo})
 	if err != nil {