diff --git a/src/helpers/alias.ts b/src/helpers/alias.ts
index a32a19eb..af1175bc 100644
--- a/src/helpers/alias.ts
+++ b/src/helpers/alias.ts
@@ -1,7 +1,7 @@
 import { uniq } from 'lodash';
 import db from './mysql';
 
-const DEFAULT_ALIAS_EXPIRY_DAYS = 30;
+export const DEFAULT_ALIAS_EXPIRY_DAYS = 30;
 
 // These types can always be executed with an alias
 const TYPES_EXECUTABLE_BY_ALIAS = [
@@ -38,25 +38,14 @@ type ExecutableType =
   | (typeof OPTIONAL_TYPES_EXECUTABLE_BY_ALIAS)[number]
   | (typeof TYPES_EXECUTABLE_BY_STARKNET_ALIAS)[number];
 
-/**
- * Checks if an alias relationship exists and is not expired
- * @param address - The original address
- * @param alias - The alias address to check
- * @param expiryDays - Number of days after which alias expires (default: 30)
- * @returns Promise<boolean> - True if valid alias exists
- */
-export async function isExistingAlias(
-  address: string,
-  alias: string,
-  expiryDays = DEFAULT_ALIAS_EXPIRY_DAYS
-): Promise<boolean> {
+export async function isExistingAlias(address: string, alias: string): Promise<boolean> {
   const query = `SELECT 1
     FROM aliases
     WHERE address = ? AND alias = ?
-      AND created > UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL ? DAY))
+      AND expiration > UNIX_TIMESTAMP(NOW())
     LIMIT 1`;
 
-  const results = await db.queryAsync(query, [address, alias, expiryDays]);
+  const results = await db.queryAsync(query, [address, alias]);
   return results.length > 0;
 }
 
diff --git a/src/writer/alias.ts b/src/writer/alias.ts
index 4a075538..30f8f928 100644
--- a/src/writer/alias.ts
+++ b/src/writer/alias.ts
@@ -1,4 +1,5 @@
 import snapshot from '@snapshot-labs/snapshot.js';
+import { DEFAULT_ALIAS_EXPIRY_DAYS } from '../helpers/alias';
 import log from '../helpers/log';
 import db from '../helpers/mysql';
 import { jsonParse } from '../helpers/utils';
@@ -14,12 +15,16 @@ export async function verify(message): Promise<any> {
     return Promise.reject('alias cannot be the same as the address');
   }
 
-  const existing = await db.queryAsync(
-    'SELECT 1 FROM aliases WHERE address = ? AND alias = ? LIMIT 1',
-    [message.address, msg.payload.alias]
-  );
-  if (existing.length > 0) {
-    return Promise.reject('alias already exists');
+  const results = await db.queryAsync('SELECT address FROM aliases WHERE alias = ?', [
+    msg.payload.alias
+  ]);
+  for (const row of results) {
+    if (row.address === message.address) {
+      return Promise.reject('alias already exists');
+    }
+  }
+  if (results.length > 0) {
+    return Promise.reject('alias is already linked to another address');
   }
 
   return true;
@@ -32,7 +37,8 @@ export async function action(message, ipfs, receipt, id): Promise<void> {
     ipfs,
     address: message.address,
     alias: msg.payload.alias,
-    created: msg.timestamp
+    created: msg.timestamp,
+    expiration: msg.timestamp + DEFAULT_ALIAS_EXPIRY_DAYS * 86400
   };
   await db.queryAsync('INSERT INTO aliases SET ?', params);
 }
diff --git a/test/fixtures/alias.ts b/test/fixtures/alias.ts
index cf3ca83f..0b6c0456 100644
--- a/test/fixtures/alias.ts
+++ b/test/fixtures/alias.ts
@@ -1,23 +1,31 @@
+import { DEFAULT_ALIAS_EXPIRY_DAYS } from '../../src/helpers/alias';
+
+const now = Math.floor(Date.now() / 1000);
+const EXPIRY_SECONDS = DEFAULT_ALIAS_EXPIRY_DAYS * 86400;
+
 export const aliasesSqlFixtures: Record<string, any>[] = [
   {
     id: '1',
     ipfs: 'Qm...',
     address: '0x0000000000000000000000000000000000000000',
     alias: '0x91FD2c8d24767db4Ece7069AA27832ffaf8590f3',
-    created: Math.floor(Date.now() / 1000)
+    created: now,
+    expiration: now + EXPIRY_SECONDS
   },
   {
     id: '2',
     ipfs: 'Qm...',
     address: '0x02a0a8f3b6097e7a6bd7649deb30715323072a159c0e6b71b689bd245c146cc0',
     alias: '0x91FD2c8d24767db4Ece7069AA27832ffaf8590f3',
-    created: Math.floor(Date.now() / 1000)
+    created: now,
+    expiration: now + EXPIRY_SECONDS
   },
   {
     id: '3',
     ipfs: 'Qm...',
     address: '0x02a0a8f3b6097e7a6bd7649deb30715323072a159c0e6b71b689bd245c146cc0',
     alias: '0x91FD2c8d24767db4Ece7069AA27832ffaf8590f4',
-    created: 1
+    created: 1,
+    expiration: 1 + EXPIRY_SECONDS
   }
 ];
diff --git a/test/integration/helpers/alias.test.ts b/test/integration/helpers/alias.test.ts
index 48f91117..cf1be008 100644
--- a/test/integration/helpers/alias.test.ts
+++ b/test/integration/helpers/alias.test.ts
@@ -41,6 +41,22 @@ describe('alias', () => {
       ).rejects.toMatch('alias already exists');
     });
 
+    it('should reject when alias is already linked to another address', async () => {
+      const alias = aliasesSqlFixtures[0].alias;
+      const differentAddress = '0x0000000000000000000000000000000000000099';
+      const msg = {
+        version: '0.1.4',
+        timestamp: Math.floor(Date.now() / 1000),
+        type: 'alias',
+        from: differentAddress,
+        payload: { alias }
+      };
+
+      await expect(
+        verify({ address: differentAddress, from: differentAddress, msg: JSON.stringify(msg) })
+      ).rejects.toMatch('alias is already linked to another address');
+    });
+
     it('should pass when alias does not exist', async () => {
       const msg = {
         version: '0.1.4',
diff --git a/test/schema.sql b/test/schema.sql
index f7e64be4..8e86dfc2 100644
--- a/test/schema.sql
+++ b/test/schema.sql
@@ -138,6 +138,7 @@ CREATE TABLE aliases (
   address VARCHAR(100) NOT NULL,
   alias VARCHAR(100) NOT NULL,
   created INT(11) NOT NULL,
+  expiration INT(11) NOT NULL,
   PRIMARY KEY (address, alias),
   INDEX ipfs (ipfs)
 );