diff --git a/server/postgres/userRepository.js b/server/postgres/userRepository.js
index c8e79d3..d9baa62 100644
--- a/server/postgres/userRepository.js
+++ b/server/postgres/userRepository.js
@@ -1,6 +1,6 @@
 const { pool } = require('./index');
 const { stableId } = require('./dualWrite');
-const { normalizeUsername } = require('../username');
+const { normalizeStoredUsername } = require('../username');
 
 const numericId = (value) => {
   const id = Number(value);
@@ -40,13 +40,16 @@ const toUser = (row) => {
 const userParams = (user, fallbackName = 'Unknown User') => {
   const id = numericId(user.id);
   if (!id) throw new Error('A valid WCA user ID is required');
-  const normalized = normalizeUsername(user.username);
+  const normalized = normalizeStoredUsername(user.username);
+  const username = normalized.username === undefined ? null : normalized.username;
+  const usernameNormalized = normalized.usernameNormalized === undefined
+    ? null : normalized.usernameNormalized;
   return [
     stableId('user', id),
     id,
     user.name || fallbackName,
-    normalized.username || null,
-    normalized.usernameNormalized || null,
+    username,
+    usernameNormalized,
     user.wcaId || null,
     {
       showWCAID: !!user.showWCAID,
diff --git a/server/postgres/userRepository.test.js b/server/postgres/userRepository.test.js
new file mode 100644
index 0000000..6ccc77f
--- /dev/null
+++ b/server/postgres/userRepository.test.js
@@ -0,0 +1,42 @@
+/** @jest-environment node */
+
+jest.mock('./index', () => ({
+  pool: {
+    query: jest.fn(),
+  },
+}));
+jest.mock('./dualWrite', () => ({
+  stableId: jest.fn(() => 'stable-user-id'),
+}));
+
+const { pool } = require('./index');
+const { updateUser } = require('./userRepository');
+
+describe('PostgreSQL user repository', () => {
+  it('keeps a legacy non-ASCII username during a profile update', async () => {
+    pool.query.mockResolvedValue({
+      rows: [{
+        id: 'stable-user-id',
+        wca_user_id: 2022,
+        name: 'Alessandro van Burken',
+        username: 'Αλέξανδρος',
+        username_normalized: null,
+        preferences: {},
+        avatar: {},
+      }],
+    });
+
+    await expect(updateUser({
+      id: 2022,
+      name: 'Alessandro van Burken',
+      username: 'Αλέξανδρος',
+    })).resolves.toMatchObject({
+      username: 'Αλέξανδρος',
+      usernameNormalized: undefined,
+    });
+
+    const params = pool.query.mock.calls[0][1];
+    expect(params[3]).toBe('Αλέξανδρος');
+    expect(params[4]).toBeNull();
+  });
+});
diff --git a/server/username.js b/server/username.js
index 8316c7e..e5d092d 100644
--- a/server/username.js
+++ b/server/username.js
@@ -51,6 +51,19 @@ const normalizeUsername = (value, { allowEmpty = true } = {}) => {
   };
 };
 
+const normalizeStoredUsername = (value) => {
+  try {
+    return normalizeUsername(value);
+  } catch (err) {
+    if (err.code !== 'INVALID_USERNAME' || typeof value !== 'string') {
+      throw err;
+    }
+
+    // Keep legacy values readable while their owner chooses a valid username.
+    return { username: value, usernameNormalized: undefined };
+  }
+};
+
 const usernameConflict = () => new UsernameError(
   'USERNAME_TAKEN',
   'Username is already in use',
@@ -117,6 +130,7 @@ module.exports = {
   findUserByUsername,
   isUsernameDuplicateKeyError,
   normalizeUsername,
+  normalizeStoredUsername,
   searchUsersByUsernamePrefix,
   updateUsername,
 };
diff --git a/server/username.test.js b/server/username.test.js
index 9dcf95b..81b8ad1 100644
--- a/server/username.test.js
+++ b/server/username.test.js
@@ -1,10 +1,10 @@
 /** @jest-environment node */
-/* eslint-env jest */
 
 const {
   canonicalizeUsername,
   findUserByUsername,
   normalizeUsername,
+  normalizeStoredUsername,
   searchUsersByUsernamePrefix,
   updateUsername,
 } = require('./username');
@@ -29,6 +29,13 @@ describe('username normalization and lookup', () => {
     });
   });
 
+  it('preserves legacy non-ASCII usernames during unrelated writes', () => {
+    expect(normalizeStoredUsername('Αλέξανδρος')).toEqual({
+      username: 'Αλέξανδρος',
+      usernameNormalized: undefined,
+    });
+  });
+
   it.each([
     'cuber.name',
     'cuber+name',