diff --git a/src/libs/fcm/getGoogleAuthToken.ts b/src/libs/fcm/getGoogleAuthToken.ts
index bfff89c..26a9ba7 100644
--- a/src/libs/fcm/getGoogleAuthToken.ts
+++ b/src/libs/fcm/getGoogleAuthToken.ts
@@ -1,6 +1,6 @@
 import { GoogleToken } from "gtoken";
 
-export async function getGoogleAuthToken(adminSdkJson: AdminSdkKey) {
+export async function getGoogleAuthToken(adminSdkJson: AdminSdkCredentials) {
   const { privateKey, clientEmail } = adminSdkJson;
 
   const gToken = new GoogleToken({
@@ -11,7 +11,7 @@ export async function getGoogleAuthToken(adminSdkJson: AdminSdkKey) {
   return gToken.getToken().then((token) => token.access_token);
 }
 
-interface AdminSdkKey {
+export interface AdminSdkCredentials {
   type: string;
   projectID: string;
   privateKeyID: string;
diff --git a/src/libs/fcm/sendFcmMessage.ts b/src/libs/fcm/sendFcmMessage.ts
index f360eb8..3a1095d 100644
--- a/src/libs/fcm/sendFcmMessage.ts
+++ b/src/libs/fcm/sendFcmMessage.ts
@@ -1,7 +1,10 @@
-import { getGoogleAuthToken } from "./getGoogleAuthToken";
+import {
+  type AdminSdkCredentials,
+  getGoogleAuthToken,
+} from "./getGoogleAuthToken";
 
 export async function sendFcmMessage(
-  adminSdkJson: string,
+  adminSdkJson: AdminSdkCredentials,
   message: FcmMessagePayload,
   isOnlyValidatingFcmMessage?: boolean,
 ) {
@@ -14,7 +17,7 @@ export async function sendFcmMessage(
         validate_only: isOnlyValidatingFcmMessage,
       }),
       headers: {
-        Authorization: `Bearer ${await getGoogleAuthToken(JSON.parse(adminSdkJson))}`,
+        Authorization: `Bearer ${await getGoogleAuthToken(adminSdkJson)}`,
       },
     },
   ).then((res) => res.json<SendFcmMessageResponse>());
diff --git a/src/libs/fcm/verifyFcm.spec.ts b/src/libs/fcm/verifyFcm.spec.ts
index 0808227..c25d2cd 100644
--- a/src/libs/fcm/verifyFcm.spec.ts
+++ b/src/libs/fcm/verifyFcm.spec.ts
@@ -7,18 +7,33 @@ import { verifyFcmToken } from "./verifyFcmToken";
 
 server.listen();
 
+const FAKE_ADMIN_SDK_JSON = {
+  type: "service_account",
+  projectID: "test-26g38",
+  privateKeyID: "privateKeyId",
+  privateKey: "privateKey",
+  clientEmail: "test@test.com",
+  clientID: "clientId",
+  authURI: "https://accounts.google.com/o/oauth2/auth",
+  tokenURI: "https://oauth2.googleapis.com/token",
+  authProviderX509CERTURL: "https://www.googleapis.com/oauth2/v1/certs",
+  clientX509CERTURL:
+    "https://www.googleapis.com/robot/v1/metadata/x509/test%40test.com",
+  universeDomain: "aniplay.com",
+};
+
 describe("verifyFcmToken", () => {
   it("valid token, returns true", async () => {
     const token =
       "7v8sy43aq0re4r8xe7rmr0cn1fsmh6phehnfla2pa73z899zmhyarivmkt4sj6pyv0py43u6p2sim6wz2vg9ypjp9rug1keoth7f6ll3gdvas4q020u3ah51r6bjgn51j6bd92ztmtof3ljpcm8q31njvndy65enm68";
-    const res = await verifyFcmToken(token, '{"clientEmail": "test@test.com"}');
+    const res = await verifyFcmToken(token, FAKE_ADMIN_SDK_JSON);
 
     expect(res).toBeTrue();
   });
 
   it("invalid token, returns false", async () => {
     const token = "abc123";
-    const res = await verifyFcmToken(token, '{"clientEmail": "test@test.com"}');
+    const res = await verifyFcmToken(token, FAKE_ADMIN_SDK_JSON);
 
     expect(res).toBeFalse();
   });
diff --git a/src/libs/fcm/verifyFcmToken.ts b/src/libs/fcm/verifyFcmToken.ts
index 95c5c93..3e041b1 100644
--- a/src/libs/fcm/verifyFcmToken.ts
+++ b/src/libs/fcm/verifyFcmToken.ts
@@ -1,8 +1,9 @@
+import type { AdminSdkCredentials } from "./getGoogleAuthToken";
 import { sendFcmMessage } from "./sendFcmMessage";
 
 export async function verifyFcmToken(
   token: string,
-  adminSdkJson: string,
+  adminSdkJson: AdminSdkCredentials,
 ): Promise<boolean> {
   return sendFcmMessage(
     adminSdkJson,