diff --git a/ts/components/ProfileEditor.tsx b/ts/components/ProfileEditor.tsx
index a903247cc975..28b4b6c34ea2 100644
--- a/ts/components/ProfileEditor.tsx
+++ b/ts/components/ProfileEditor.tsx
@@ -36,6 +36,7 @@ import {
 } from './conversation/conversation-details/ConversationDetailsIcon';
 import { Spinner } from './Spinner';
 import { UsernameSaveState } from '../state/ducks/conversationsEnums';
+import { MAX_USERNAME, MIN_USERNAME } from '../types/Username';
 
 export enum EditState {
   None = 'None',
@@ -124,26 +125,24 @@ function getUsernameInvalidKey(
     return undefined;
   }
 
-  const min = 3;
-  if (username.length < min) {
+  if (username.length < MIN_USERNAME) {
     return {
       key: 'ProfileEditor--username--check-character-min',
-      replacements: { min },
+      replacements: { min: MIN_USERNAME },
     };
   }
 
   if (!/^[0-9a-z_]+$/.test(username)) {
     return { key: 'ProfileEditor--username--check-characters' };
   }
-  if (/^[0-9]/.test(username)) {
+  if (!/^[a-z_]/.test(username)) {
     return { key: 'ProfileEditor--username--check-starting-character' };
   }
 
-  const max = 25;
-  if (username.length > max) {
+  if (username.length > MAX_USERNAME) {
     return {
       key: 'ProfileEditor--username--check-character-max',
-      replacements: { max },
+      replacements: { max: MAX_USERNAME },
     };
   }
 
diff --git a/ts/test-node/types/Username_test.ts b/ts/test-node/types/Username_test.ts
index c097f0911e30..016161b93b9c 100644
--- a/ts/test-node/types/Username_test.ts
+++ b/ts/test-node/types/Username_test.ts
@@ -12,20 +12,20 @@ describe('Username', () => {
     it('matches invalid username searches', () => {
       assert.strictEqual(getUsernameFromSearch('username!'), 'username!');
       assert.strictEqual(getUsernameFromSearch('1username'), '1username');
-      assert.strictEqual(getUsernameFromSearch('us'), 'us');
+      assert.strictEqual(getUsernameFromSearch('use'), 'use');
       assert.strictEqual(
-        getUsernameFromSearch('username901234567890123456'),
-        'username901234567890123456'
+        getUsernameFromSearch('username9012345678901234567'),
+        'username9012345678901234567'
       );
     });
 
     it('matches valid username searches', () => {
       assert.strictEqual(getUsernameFromSearch('username_34'), 'username_34');
       assert.strictEqual(getUsernameFromSearch('u5ername'), 'u5ername');
-      assert.strictEqual(getUsernameFromSearch('use'), 'use');
+      assert.strictEqual(getUsernameFromSearch('user'), 'user');
       assert.strictEqual(
-        getUsernameFromSearch('username90123456789012345'),
-        'username90123456789012345'
+        getUsernameFromSearch('username901234567890123456'),
+        'username901234567890123456'
       );
     });
 
@@ -57,15 +57,16 @@ describe('Username', () => {
     it('does not match invalid username searches', () => {
       assert.isFalse(isValidUsername('username!'));
       assert.isFalse(isValidUsername('1username'));
-      assert.isFalse(isValidUsername('us'));
-      assert.isFalse(isValidUsername('username901234567890123456'));
+      assert.isFalse(isValidUsername('use'));
+      assert.isFalse(isValidUsername('username9012345678901234567'));
     });
 
     it('matches valid usernames', () => {
       assert.isTrue(isValidUsername('username_34'));
       assert.isTrue(isValidUsername('u5ername'));
-      assert.isTrue(isValidUsername('use'));
-      assert.isTrue(isValidUsername('username90123456789012345'));
+      assert.isTrue(isValidUsername('_username'));
+      assert.isTrue(isValidUsername('user'));
+      assert.isTrue(isValidUsername('username901234567890123456'));
     });
 
     it('does not match valid and invalid usernames with @ prefix or suffix', () => {
diff --git a/ts/types/Username.ts b/ts/types/Username.ts
index a65696580b45..d4699fe5d748 100644
--- a/ts/types/Username.ts
+++ b/ts/types/Username.ts
@@ -1,8 +1,11 @@
 // Copyright 2021 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
+export const MAX_USERNAME = 26;
+export const MIN_USERNAME = 4;
+
 export function isValidUsername(searchTerm: string): boolean {
-  return /^[a-z][0-9a-z_]{2,24}$/.test(searchTerm);
+  return /^[a-z_][0-9a-z_]{3,25}$/.test(searchTerm);
 }
 
 export function getUsernameFromSearch(searchTerm: string): string | undefined {