diff --git a/lib/BankLetter.js b/lib/BankLetter.js
index 1a98282..eb732ad 100644
--- a/lib/BankLetter.js
+++ b/lib/BankLetter.js
@@ -24,6 +24,12 @@ const registerHelpers = () => {
 		return digest.toUpperCase().match(/.{1,2}/g).join(' ');
 	});
 };
+
+const writeFile = (file, content) => new Promise((resolve, reject) => fs.writeFile(file, content, (err, result) => {
+	if (err)
+		return reject(err);
+	return resolve(result);
+}));
 module.exports = class BankLetter {
 	constructor({
 		client,
@@ -55,13 +61,7 @@ module.exports = class BankLetter {
 
 	async serialize(path) {
 		const letter = await this.generate();
-
-		try {
-			fs.writeFileSync(path, letter);
-		} catch (error) {
-			throw error;
-		}
-
-		return new Promise(resolve => resolve(true));
+		await writeFile(path, letter);
+		return true;
 	}
 };