--- a/cubicweb/dataimport/importer.py	Tue Jun 28 15:01:40 2016 +0200
+++ b/cubicweb/dataimport/importer.py	Wed Jun 29 09:12:02 2016 +0200
@@ -216,7 +216,9 @@
                     if (rschema.final and eschema.has_metadata(rtype, 'format')
                             and not rtype + '_format' in entity_dict):
                         entity_dict[rtype + '_format'] = u'text/plain'
-                    if rschema.final and eschema.rdef(rtype).object.type == 'Bytes':
+                    if (rschema.final
+                            and eschema.rdef(rtype).object.type == 'Bytes'
+                            and not isinstance(entity_dict[rtype], Binary)):
                         entity_dict[rtype] = Binary(entity_dict[rtype])
                 else:
                     del entity_dict[key]

--- a/cubicweb/dataimport/test/unittest_importer.py	Tue Jun 28 15:01:40 2016 +0200
+++ b/cubicweb/dataimport/test/unittest_importer.py	Wed Jun 29 09:12:02 2016 +0200
@@ -18,7 +18,7 @@
 
 from logilab.common.testlib import TestCase, unittest_main
 
-from cubicweb import ValidationError
+from cubicweb import Binary, ValidationError
 from cubicweb.devtools.testlib import CubicWebTC
 from cubicweb.dataimport import RQLObjectStore, ucsvreader
 from cubicweb.dataimport.importer import (ExtEntity, ExtEntitiesImporter, RelationMapping,
@@ -74,6 +74,18 @@
             entity = cnx.find('Personne').one()
             self.assertEqual(entity.photo.getvalue(), b'poilu')
 
+    def test_binary_in_values(self):
+        with self.admin_access.repo_cnx() as cnx:
+            importer = self.importer(cnx)
+            # Use a list to put a Binary in "values" (since Binary is not
+            # hashable, a set cannot be used).
+            personne = ExtEntity('Personne', 1, {'photo': [Binary(b'poilu')],
+                                                 'nom': set([u'alf'])})
+            importer.import_entities([personne])
+            cnx.commit()
+            entity = cnx.find('Personne').one()
+            self.assertEqual(entity.photo.getvalue(), b'poilu')
+
     def test_import_missing_required_attribute(self):
         """Check import of ext entity with missing required attribute"""
         with self.admin_access.repo_cnx() as cnx: