diff --git a/src/hyperjump-json-schema.test.js b/src/hyperjump-json-schema.test.js
index 45cbd1c..7ac8f4c 100644
--- a/src/hyperjump-json-schema.test.js
+++ b/src/hyperjump-json-schema.test.js
@@ -14,6 +14,7 @@ import "@hyperjump/json-schema/formats";
 import { BASIC } from "@hyperjump/json-schema/experimental";
 import { jsonSchemaErrors } from "../src/index.js";
 import { FluentBundle, FluentResource } from "@fluent/bundle";
+import { translations } from "./translations/index.js";
 
 /**
  * @import { SchemaObject } from "@hyperjump/json-schema"
@@ -153,8 +154,8 @@ const isCompatible = (compatibility, versionUnderTest) => {
 };
 
 /** @type (messageId: string, messageParams: MessageParams) => string */
-const getMessage = await (async function () {
-  const ftl = await readFile(`${import.meta.dirname}/translations/en-US.ftl`, "utf-8");
+const getMessage = (function () {
+  const ftl = translations["en-US"];
   const resource = new FluentResource(ftl);
   const bundle = new FluentBundle("en-US");
   bundle.addResource(resource);
diff --git a/src/index.d.ts b/src/index.d.ts
index 9f3e106..2cb2687 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -172,10 +172,10 @@ export type ContainsRange = {
 export const validate: (
   (schemaUri: string) => Promise<EvaluateInstance>
 ) & (
-  (schemaUri: string, instance: Json, options?: ValidationOptions) => Promise<ValidationResult>
+  (schemaUri: string, instance: Json, options?: ValidationOptions) => ValidationResult
 );
 
-export type EvaluateInstance = (instance: Json, options?: ValidationOptions) => Promise<ValidationResult>;
+export type EvaluateInstance = (instance: Json, options?: ValidationOptions) => ValidationResult;
 
 export type ValidationOptions = {
   /**
diff --git a/src/json-schema-errors.js b/src/json-schema-errors.js
index da0bcd2..66ed333 100644
--- a/src/json-schema-errors.js
+++ b/src/json-schema-errors.js
@@ -24,7 +24,7 @@ export const jsonSchemaErrors = async (errorOutput, schemaUri, instance, options
     errorIndex,
     plugins: [...ast.plugins]
   });
-  const localization = await Localization.forLocale(options.locale ?? "en-US");
+  const localization = Localization.forLocale(options.locale ?? "en-US");
   return getErrors(normalizedErrors, rootInstance, localization, ast);
 };
 
@@ -254,9 +254,9 @@ export const validate = async (schemaUri, instance, options) => {
   }
 };
 
-/** @type (compiledSchema: CompiledSchema, instance: API.Json, options?: API.ValidationOptions) => Promise<API.ValidationResult> */
-const evaluateCompiledSchema = async (compiledSchema, instance, options = {}) => {
-  const localization = await Localization.forLocale(options.locale ?? "en-US");
+/** @type (compiledSchema: CompiledSchema, instance: API.Json, options?: API.ValidationOptions) => API.ValidationResult */
+const evaluateCompiledSchema = (compiledSchema, instance, options = {}) => {
+  const localization = Localization.forLocale(options.locale ?? "en-US");
   const jsonNode = Instance.fromJs(instance);
   const outputPlugin = new JsonSchemaErrorsOutputPlugin();
   const context = {
diff --git a/src/localization.js b/src/localization.js
index e810d76..f6abc3c 100644
--- a/src/localization.js
+++ b/src/localization.js
@@ -1,4 +1,4 @@
-import { readFile } from "node:fs/promises";
+import { translations } from "./translations/index.js";
 import { FluentBundle, FluentResource } from "@fluent/bundle";
 
 /**
@@ -21,18 +21,17 @@ export class Localization {
     this.conjunction = new Intl.ListFormat(this.locale, { type: "conjunction" });
   }
 
-  /** @type (locale: string) => Promise<Localization> */
-  static async forLocale(locale) {
+  /** @type (locale: string) => Localization */
+  static forLocale(locale) {
     if (!localizationCache.has(locale)) {
-      try {
-        const ftl = await readFile(`${import.meta.dirname}/translations/${locale}.ftl`, "utf-8");
-        const resource = new FluentResource(ftl);
-        const bundle = new FluentBundle(locale);
-        bundle.addResource(resource);
-        localizationCache.set(locale, new Localization(locale, bundle));
-      } catch (error) {
-        throw Error(`The ${locale} locale is not supported.`, { cause: error });
+      const ftl = translations[locale];
+      if (!ftl) {
+        throw Error(`The ${locale} locale is not supported.`);
       }
+      const resource = new FluentResource(ftl);
+      const bundle = new FluentBundle(locale);
+      bundle.addResource(resource);
+      localizationCache.set(locale, new Localization(locale, bundle));
     }
 
     return /** @type Localization */ (localizationCache.get(locale));
diff --git a/src/localization.test.js b/src/localization.test.js
index 388e47c..56bce3d 100644
--- a/src/localization.test.js
+++ b/src/localization.test.js
@@ -1,25 +1,24 @@
-import { afterEach, beforeEach, describe, expect, test } from "vitest";
-import { rm, writeFile } from "node:fs/promises";
+import { beforeAll, afterAll, describe, expect, test } from "vitest";
+import { translations } from "./translations/index.js";
 import { Localization } from "./localization.js";
 
 describe("Localization", () => {
   const fixtureLocale = "fx-TR";
 
-  beforeEach(async () => {
-    await writeFile(`src/translations/${fixtureLocale}.ftl`, "example = message");
+  beforeAll(() => {
+    translations[fixtureLocale] = `test = unsupported locale`;
   });
 
-  afterEach(async () => {
-    await rm(`src/translations/${fixtureLocale}.ftl`);
+  afterAll(() => {
+    delete translations[fixtureLocale];
   });
 
-  test("unsupported locale", async () => {
-    const localization = Localization.forLocale("xx-XX");
-    await expect(localization).rejects.to.throw(Error);
+  test("unsupported locale", () => {
+    expect(() => Localization.forLocale("xx-XX")).to.throw(Error);
   });
 
-  test("unsupported message", async () => {
-    const localization = await Localization.forLocale(fixtureLocale);
+  test("unsupported message", () => {
+    const localization = Localization.forLocale(fixtureLocale);
     expect(() => localization.getBooleanSchemaErrorMessage()).to.throw(Error);
   });
 });
diff --git a/src/normalization.test.js b/src/normalization.test.js
index 1459330..95131b2 100644
--- a/src/normalization.test.js
+++ b/src/normalization.test.js
@@ -7,9 +7,9 @@ import { Localization } from "./localization.js";
  * @import { OutputFormat } from "./index.js";
  */
 
-describe("Normalization", async () => {
+describe("Normalization", () => {
   const schemaUri = "https://example.com/main";
-  const localization = await Localization.forLocale("en-US");
+  const localization = Localization.forLocale("en-US");
 
   afterEach(() => {
     unregisterSchema(schemaUri);
diff --git a/src/translations/en-US.ftl b/src/translations/en-US.js
similarity index 99%
rename from src/translations/en-US.ftl
rename to src/translations/en-US.js
index 4999fbf..731cc41 100644
--- a/src/translations/en-US.ftl
+++ b/src/translations/en-US.js
@@ -1,3 +1,4 @@
+export default `
 // Any type keywords
 boolean-schema-message = A value is not allowed here
 type-message = Expected a {$expectedTypes}
@@ -47,3 +48,4 @@ oneOf-message = Expected the value to match exactly one alternative, {$matchCoun
  *[other] but more than one
 } matched
 not-message = Expected a value that doesn't match the 'not' schema
+`;
diff --git a/src/translations/index.js b/src/translations/index.js
new file mode 100644
index 0000000..ce6443e
--- /dev/null
+++ b/src/translations/index.js
@@ -0,0 +1,6 @@
+import enUS from "./en-US.js";
+
+/** @type Record<string, string> */
+export const translations = {
+  "en-US": enUS
+};