diff --git a/src/controllers/token/index.ts b/src/controllers/token/index.ts
index fd6abd7..b8c6148 100644
--- a/src/controllers/token/index.ts
+++ b/src/controllers/token/index.ts
@@ -3,6 +3,7 @@ import { env } from "hono/adapter";
 import mapKeys from "lodash.mapkeys";
 
 import { Case, changeStringCase } from "~/libs/changeStringCase";
+import { TokenAlreadyExistsError } from "~/libs/errors/TokenAlreadyExists";
 import type { AdminSdkCredentials } from "~/libs/fcm/getGoogleAuthToken";
 import { verifyFcmToken } from "~/libs/fcm/verifyFcmToken";
 import { readEnvVariable } from "~/libs/readEnvVariable";
@@ -69,7 +70,7 @@ app.openapi(route, async (c) => {
 
     await saveToken(env(c, "workerd"), deviceId, token, username);
   } catch (error) {
-    if (error.message === "Token already exists in the database") {
+    if (error instanceof TokenAlreadyExistsError) {
       return c.json(ErrorResponse, 412);
     }
 
diff --git a/src/libs/errors/TokenAlreadyExists.ts b/src/libs/errors/TokenAlreadyExists.ts
new file mode 100644
index 0000000..abdaa41
--- /dev/null
+++ b/src/libs/errors/TokenAlreadyExists.ts
@@ -0,0 +1,5 @@
+export class TokenAlreadyExistsError extends Error {
+  constructor() {
+    super("Token already exists in the database");
+  }
+}
diff --git a/src/models/token.ts b/src/models/token.ts
index ecd042b..cb8eaa3 100644
--- a/src/models/token.ts
+++ b/src/models/token.ts
@@ -1,5 +1,6 @@
 import { eq, or, sql } from "drizzle-orm";
 
+import { TokenAlreadyExistsError } from "~/libs/errors/TokenAlreadyExists";
 import type { Env } from "~/types/env";
 
 import { getDb } from "./db";
@@ -34,7 +35,7 @@ export function saveToken(
         !existingToken.username &&
         !username
       ) {
-        throw new Error("Token already exists in the database");
+        throw new TokenAlreadyExistsError();
       }
 
       return updateToken(env, deviceId, token, username);