diff --git a/trytond/doc/topics/domain.rst b/trytond/doc/topics/domain.rst
index e65a166f18..e61456ff47 100644
--- a/trytond/doc/topics/domain.rst
+++ b/trytond/doc/topics/domain.rst
@@ -40,6 +40,7 @@ by this pattern::
     .. note::
       Negative operators match records for which any of the field before the
       last dot is empty.
+      Except if the operand is or contains ``None``.
 
     .. warning::
         For :class:`trytond.model.fields.Reference`, an extra ending clause is
diff --git a/trytond/trytond/model/fields/many2one.py b/trytond/trytond/model/fields/many2one.py
index d7714a12b4..3c6ec233e6 100644
--- a/trytond/trytond/model/fields/many2one.py
+++ b/trytond/trytond/model/fields/many2one.py
@@ -280,7 +280,10 @@ class Many2One(Field):
             target_table, _ = target_tables[None]
             _, expression = Target.search_domain(
                 target_domain, tables=target_tables)
-        if operator.startswith('not') or operator == '!=':
+        if ((operator.startswith('not') and not (
+                        operator == 'not in'
+                        and None in value))
+                or (operator == '!=' and value is not None)):
             expression |= column == Null
         return expression
 
diff --git a/trytond/trytond/model/fields/reference.py b/trytond/trytond/model/fields/reference.py
index 6b30e9e884..232e3a0b88 100644
--- a/trytond/trytond/model/fields/reference.py
+++ b/trytond/trytond/model/fields/reference.py
@@ -216,7 +216,10 @@ class Reference(SelectionMixin, Field):
         expression = (
             self.sql_id(column, Model).in_(query)
             & column.like(target + ',%'))
-        if operator.startswith('not') or operator == '!=':
+        if ((operator.startswith('not') and not (
+                        operator == 'not in'
+                        and None in value))
+                or (operator == '!=' and value is not None)):
             expression |= column == Null
         return expression
 
diff --git a/trytond/trytond/tests/test_field_many2one.py b/trytond/trytond/tests/test_field_many2one.py
index 7993d5e282..b992904cea 100644
--- a/trytond/trytond/tests/test_field_many2one.py
+++ b/trytond/trytond/tests/test_field_many2one.py
@@ -220,6 +220,21 @@ class FieldMany2OneTestCase(TestCase):
                 ])
         self.assertListEqual(result, [record])
 
+        result = Many2One.search([
+                ('many2one.value', '!=', None),
+                ])
+        self.assertListEqual(result, [])
+
+        result = Many2One.search([
+                ('many2one.value', 'not in', [1]),
+                ])
+        self.assertListEqual(result, [record])
+
+        result = Many2One.search([
+                ('many2one.value', 'not in', [1, None]),
+                ])
+        self.assertListEqual(result, [])
+
     @with_transaction()
     def test_set_instance(self):
         "Test set instance"
diff --git a/trytond/trytond/tests/test_field_reference.py b/trytond/trytond/tests/test_field_reference.py
index 4559ab15a9..76a48860e5 100644
--- a/trytond/trytond/tests/test_field_reference.py
+++ b/trytond/trytond/tests/test_field_reference.py
@@ -375,6 +375,25 @@ class FieldReferenceTestCase(TestCase):
 
         self.assertListEqual(result, [reference])
 
+        result = Reference.search([
+                ('reference.name', '!=', None, Target.__name__),
+                ])
+
+        self.assertListEqual(result, [])
+
+        result = Reference.search([
+                ('reference.name', 'not in', ["Target"], Target.__name__),
+                ])
+
+        self.assertListEqual(result, [reference])
+
+        result = Reference.search([
+                ('reference.name', 'not in', ["Target", None],
+                    Target.__name__),
+                ])
+
+        self.assertListEqual(result, [])
+
     @with_transaction()
     def test_write_string(self):
         "Test write reference string"