diff --git a/package.json b/package.json
index 81243ef..cb90a43 100644
--- a/package.json
+++ b/package.json
@@ -28,7 +28,7 @@
   "scripts": {
     "prepublishOnly": "pnpm run build",
     "lint": "eslint --ext .ts,.tsx . && prettier --check .",
-    "test": "vitest --coverage",
+    "test": "vitest --coverage --coverage.include=src/**",
     "test:ci": "tsc --noEmit && vitest --coverage --coverage.reporter=lcov --coverage.include=src/**",
     "docs": "typedoc --options typedoc.json",
     "build": "cross-env NODE_ENV=production tsup --onSuccess \"node scripts/build-umd.mjs\"",
diff --git a/src/i18n.ts b/src/i18n.ts
index 3487690..80b42db 100644
--- a/src/i18n.ts
+++ b/src/i18n.ts
@@ -97,8 +97,12 @@ export class I18n {
         if (args) {
           const option = args[":option"];
           if (option != null) {
-            const newKey = `${key}.${option}`;
-            key = flatLocale[newKey] ? newKey : `${key}.other`;
+            let newKey: string;
+            key =
+              flatLocale[(newKey = `${key}.${option}`)] ||
+              flatLocale[(newKey = `${key}.other`)]
+                ? newKey
+                : key;
           }
           let fn = localeFns.get(key);
           fn ||
diff --git a/test/i18n.test.ts b/test/i18n.test.ts
index 288d7e4..2e03815 100644
--- a/test/i18n.test.ts
+++ b/test/i18n.test.ts
@@ -152,6 +152,17 @@ describe("template t function", () => {
     expect(i18n.t("apple", { ":option": 3 })).toBe("3 apples");
   });
 
+  it("should support :option without sub keys", () => {
+    const locales: Locales = {
+      en: {
+        message: "{{:option}} world",
+      },
+    };
+    const i18n = new I18n("en", locales);
+    expect(i18n.t("message", { ":option": "hello" })).toBe("hello world");
+    expect(i18n.t("message", { ":option": "bye" })).toBe("bye world");
+  });
+
   it("should return key if message not exists", () => {
     const i18n = new I18n("en", {});
     expect(i18n.t("fruit")).toBe("fruit");