diff --git a/AUTHORS b/AUTHORS
index 084c0129..b00b0692 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -139,6 +139,7 @@ that much better:
  * lraucy
  * hellysmile
  * Jaepil Jeong
+ * Daniil Sharou
  * Stefan Wójcik
  * Pete Campton
  * Martyn Smith
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 01471461..45470000 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -51,6 +51,7 @@ Changes in 0.8.X
 
 Changes in 0.7.10
 =================
+- Fix UnicodeEncodeError for dbref (#278)
 - Allow construction using positional parameters (#268)
 - Updated EmailField length to support long domains (#243)
 - Added 64-bit integer support (#251)
diff --git a/mongoengine/dereference.py b/mongoengine/dereference.py
index 1e220d47..e5e8886b 100644
--- a/mongoengine/dereference.py
+++ b/mongoengine/dereference.py
@@ -115,7 +115,7 @@ class DeReference(object):
         object_map = {}
         for col, dbrefs in self.reference_map.iteritems():
             keys = object_map.keys()
-            refs = list(set([dbref for dbref in dbrefs if str(dbref) not in keys]))
+            refs = list(set([dbref for dbref in dbrefs if unicode(dbref).encode('utf-8') not in keys]))
             if hasattr(col, 'objects'):  # We have a document class for the refs
                 references = col.objects.in_bulk(refs)
                 for key, doc in references.iteritems():
diff --git a/tests/test_dereference.py b/tests/test_dereference.py
index f8925238..10c3422c 100644
--- a/tests/test_dereference.py
+++ b/tests/test_dereference.py
@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 from __future__ import with_statement
 import sys
 sys.path[0:0] = [""]
@@ -1153,5 +1154,29 @@ class FieldTest(unittest.TestCase):
         self.assertTrue(tuple(x.items[0]) in tuples)
         self.assertTrue(x.items[0] in tuples)
 
+    def test_non_ascii_pk(self):
+        """
+        Ensure that dbref conversion to string does not fail when
+        non-ascii characters are used in primary key
+        """
+        class Brand(Document):
+            title = StringField(max_length=255, primary_key=True)
+
+        class BrandGroup(Document):
+            title = StringField(max_length=255, primary_key=True)
+            brands = SortedListField(ReferenceField("Brand", dbref=True))
+
+        Brand.drop_collection()
+        BrandGroup.drop_collection()
+
+        brand1 = Brand(title="Moschino").save()
+        brand2 = Brand(title=u"Денис Симачёв").save()
+
+        BrandGroup(title="top_brands", brands=[brand1, brand2]).save()
+        brand_groups = BrandGroup.objects().all()
+
+        self.assertEqual(2, len([brand for bg in brand_groups for brand in bg.brands]))
+
 if __name__ == '__main__':
     unittest.main()
+