diff --git a/src/handlers/users.test.ts b/src/handlers/users.test.ts
index cb86e11..b15b354 100644
--- a/src/handlers/users.test.ts
+++ b/src/handlers/users.test.ts
@@ -33,15 +33,14 @@ const matrixUser: MatrixUser = {
 }
 
 const nonce = 'test-nonce'
+const mac = 'be0537407ab3c82de908c5763185556e98a7211c'
 
 test('mapping users', () => {
   expect(mapUser(rcUser)).toStrictEqual(matrixUser)
 })
 
 test('generating correct hmac', () => {
-  expect(generateHmac({ ...matrixUser, nonce })).toStrictEqual(
-    'be0537407ab3c82de908c5763185556e98a7211c'
-  )
+  expect(generateHmac({ ...matrixUser, nonce })).toStrictEqual(mac)
 })
 
 test('creating users', async () => {
@@ -61,14 +60,11 @@ test('creating users', async () => {
   })
 
   expect(mockedAxios.get).toHaveBeenCalledWith('/_synapse/admin/v1/register')
-  expect(mockedAxios.post).toHaveBeenCalled()
-  // The following test fails with an incorrect return value, for whatever reason.
-  // Probably because of mutated call logs in jest due to the `delete` or sth.
-  // expect(mockedAxios.post).toHaveBeenCalledWith('/_synapse/admin/v1/register', {
-  //   ...matrixUser,
-  //   nonce,
-  //   mac: 'be0537407ab3c82de908c5763185556e98a7211c',
-  // })
+  expect(mockedAxios.post).toHaveBeenCalledWith('/_synapse/admin/v1/register', {
+    ...matrixUser,
+    nonce,
+    mac,
+  })
 
   expect(mockedStorage.createMembership).toHaveBeenCalledWith(
     rcUser.__rooms[0],
diff --git a/src/handlers/users.ts b/src/handlers/users.ts
index b6a59bc..85680fb 100644
--- a/src/handlers/users.ts
+++ b/src/handlers/users.ts
@@ -76,16 +76,13 @@ async function parseUserMemberships(rcUser: RcUser): Promise<void> {
 
 export async function createUser(rcUser: RcUser): Promise<MatrixUser> {
   const user = mapUser(rcUser)
-  user.nonce = await getUserRegistrationNonce()
-  user.mac = generateHmac(user)
-  const accessToken = await registerUser(user)
+  const nonce = await getUserRegistrationNonce()
+  const mac = generateHmac({ ...user, nonce })
+  const accessToken = await registerUser({ ...user, nonce, mac })
   user.user_id = accessToken.user_id
   user.access_token = accessToken.access_token
   log.info(`User ${rcUser.username} created:`, user)
 
-  delete user.nonce
-  delete user.mac
-
   await parseUserMemberships(rcUser)
 
   return user