diff --git a/pykolab/auth/ldap/auth_cache.py b/pykolab/auth/ldap/auth_cache.py
--- a/pykolab/auth/ldap/auth_cache.py
+++ b/pykolab/auth/ldap/auth_cache.py
@@ -139,6 +139,9 @@
 
         db.commit()
     elif len(_entries) == 1:
+        if not isinstance(value, unicode):
+            value = unicode(value, 'utf-8')
+
         if not _entries[0].value == value:
             _entries[0].value = value
 
diff --git a/tests/unit/test-020-auth_cache.py b/tests/unit/test-020-auth_cache.py
--- a/tests/unit/test-020-auth_cache.py
+++ b/tests/unit/test-020-auth_cache.py
@@ -111,3 +111,49 @@
 
         result = auth_cache.get_entry('v' + 'e'*512 + 'rylongkey')
         self.assertEqual(result, 'v' + 'e'*512 + 'rylongvalue')
+
+    def test_006_plain_update(self):
+        auth_cache.set_entry(
+                'somekey',
+                'ou=People,dc=example,dc=org2'
+            )
+
+        result = auth_cache.get_entry('somekey')
+        self.assertEqual(result, 'ou=People,dc=example,dc=org2')
+
+    def test_007_plain_encoding_update(self):
+        auth_cache.set_entry(
+                'somekey2',
+                'ou=Geschäftsbereich,ou=People,dc=example,dc=org2'
+            )
+
+        result = auth_cache.get_entry('somekey2')
+        self.assertEqual(result, 'ou=Gesch\xc3\xa4ftsbereich,ou=People,dc=example,dc=org2')
+
+    def test_008_unicode_update(self):
+        auth_cache.set_entry(
+                'somekey3',
+                u'ou=Geschäftsbereich,ou=People,dc=example,dc=org2'
+            )
+
+        result = auth_cache.get_entry('somekey3')
+        self.assertEqual(result, 'ou=Gesch\xc3\xa4ftsbereich,ou=People,dc=example,dc=org2')
+
+    @unittest.skip("Double encoding or decoding")
+    def test_009_unicode_escape_update(self):
+        auth_cache.set_entry(
+                'somekey4',
+                u'ou=Gesch\xc3\xa4ftsbereich,ou=People,dc=example,dc=org2'
+            )
+
+        result = auth_cache.get_entry('somekey4')
+        self.assertEqual(result, u'ou=Gesch\xc3\xa4ftsbereich,ou=People,dc=example,dc=org2')
+
+    def test_010_longkey_update(self):
+        auth_cache.set_entry(
+                'v' + 'e'*512 + 'rylongkey',
+                'v' + 'e'*512 + 'rylongvalue2'
+            )
+
+        result = auth_cache.get_entry('v' + 'e'*512 + 'rylongkey')
+        self.assertEqual(result, 'v' + 'e'*512 + 'rylongvalue2')