diff --git a/modoboa/admin/tests/test_account.py b/modoboa/admin/tests/test_account.py
index f1d3114e9..016c740b2 100644
--- a/modoboa/admin/tests/test_account.py
+++ b/modoboa/admin/tests/test_account.py
@@ -18,6 +18,31 @@ from .. import factories
 from .. import models
 
 
+class AuthenticationTestCase(ModoTestCase):
+    """Check authentication."""
+
+    @classmethod
+    def setUpTestData(cls):
+        """Create test data."""
+        super(AuthenticationTestCase, cls).setUpTestData()
+        cls.mb = factories.MailboxFactory(
+            domain__name="test.com", address="user",
+            user__username="user@test.com",
+            user__groups=('SimpleUsers',)
+        )
+
+    def test_authentication_unicode(self):
+        """Test with unicode password."""
+        self.client.logout()
+        password = "Tété1234"
+        self.mb.user.set_password(password)
+        self.mb.user.save(update_fields=["password"])
+        data = {"username": self.mb.full_address, "password": password}
+        response = self.client.post(reverse("core:login"), data)
+        self.assertEqual(response.status_code, 302)
+        self.assertTrue(response.url.endswith(reverse("core:user_index")))
+
+
 class AccountTestCase(ModoTestCase):
 
     @classmethod
diff --git a/modoboa/core/tests/test_authentication.py b/modoboa/core/tests/test_authentication.py
index 0575a88aa..4b05d4219 100644
--- a/modoboa/core/tests/test_authentication.py
+++ b/modoboa/core/tests/test_authentication.py
@@ -1,3 +1,5 @@
+# coding: utf8
+
 """Tests for core application."""
 
 from __future__ import unicode_literals
diff --git a/modoboa/lib/cryptutils.py b/modoboa/lib/cryptutils.py
index 758a75052..d7f25c5ca 100644
--- a/modoboa/lib/cryptutils.py
+++ b/modoboa/lib/cryptutils.py
@@ -36,9 +36,10 @@ def encrypt(clear):
     cipher = Cipher(algorithms.AES(key), modes.ECB(), backend=backend)
     encryptor = cipher.encryptor()
     block_size = algorithms.AES.block_size
+    clear = force_bytes(clear)
     if len(clear) % block_size:
-        clear += " " * (block_size - len(clear) % block_size)
-    ct = encryptor.update(force_bytes(clear)) + encryptor.finalize()
+        clear += b" " * (block_size - len(clear) % block_size)
+    ct = encryptor.update(clear) + encryptor.finalize()
     return force_text(base64.b64encode(ct))