diff --git a/stacosys/core/imap.py b/stacosys/core/imap.py
index 2970e15..b53da1d 100755
--- a/stacosys/core/imap.py
+++ b/stacosys/core/imap.py
@@ -121,7 +121,7 @@ def _email_non_ascii_to_uft8(string):
     # characters inside e-mail in a way that won’t confuse e-mail servers
     subject = ""
     for v, charset in email.header.decode_header(string):
-        if charset is None:
+        if charset is None or charset == 'unknown-8bit':
             if type(v) is bytes:
                 v = v.decode()
             subject = subject + v
diff --git a/tests/test_imap.py b/tests/test_imap.py
new file mode 100644
index 0000000..400ecbf
--- /dev/null
+++ b/tests/test_imap.py
@@ -0,0 +1,17 @@
+#!/usr/bin/python
+# -*- coding: UTF-8 -*-
+
+import os
+import unittest
+
+from stacosys.core.imap import _to_utf8, _email_non_ascii_to_uft8
+from email.header import Header
+
+
+class ImapTestCase(unittest.TestCase):
+
+    def test_utf8_decode(self):
+        h = Header(s="Chez Darty vous avez re\udcc3\udca7u un nouvel aspirateur Vacuum gratuit jl8nz",
+                   charset="unknown-8bit")
+        decoded = _email_non_ascii_to_uft8(h)
+        self.assertEquals(decoded, "Chez Darty vous avez reçu un nouvel aspirateur Vacuum gratuit jl8nz")