diff --git a/trytond/trytond/model/modelsql.py b/trytond/trytond/model/modelsql.py
index 96bde29b9b..26422f8d42 100644
--- a/trytond/trytond/model/modelsql.py
+++ b/trytond/trytond/model/modelsql.py
@@ -22,6 +22,7 @@ from trytond.pool import Pool
 from trytond.pyson import PYSONDecoder, PYSONEncoder
 from trytond.rpc import RPC
 from trytond.tools import cursor_dict, grouped_slice, reduce_ids
+from trytond.tools.domain_inversion import simplify
 from trytond.transaction import (
     Transaction, inactive_records, record_cache_size, without_check_access)
 
@@ -1691,6 +1692,21 @@ class ModelSQL(ModelStorage):
         pool = Pool()
         Rule = pool.get('ir.rule')
 
+        def convert(domain):
+            if is_leaf(domain):
+                fname, *_ = domain[0].split('.', 1)
+                field = cls._fields[fname]
+                if isinstance(field, fields.Function) and field.searcher:
+                    new_leaf = getattr(cls, field.searcher)(fname, domain)
+                    return new_leaf
+                else:
+                    return domain
+            elif isinstance(domain, str):
+                return domain
+            else:
+                return [convert(d) for d in domain]
+
+        domain = simplify(convert(domain))
         rule_domain = Rule.domain_get(cls.__name__, mode='read')
         joined_domains = None
         if domain and domain[0] == 'OR':
diff --git a/trytond/trytond/tests/modelsql.py b/trytond/trytond/tests/modelsql.py
index c2fa05dcb7..669441dee9 100644
--- a/trytond/trytond/tests/modelsql.py
+++ b/trytond/trytond/tests/modelsql.py
@@ -152,6 +152,13 @@ class ModelSQLSearchOR2Union(ModelSQL):
             }
         return [table.integer + target.id]
 
+    @classmethod
+    def search_rec_name(cls, name, clause):
+        return ['OR',
+            ('name',) + clause[1:],
+            ('targets.name',) + clause[1:],
+            ]
+
 
 class ModelSQLSearchOR2UnionTarget(ModelSQL):
     "ModelSQL Target to test read"
diff --git a/trytond/trytond/tests/test_modelsql.py b/trytond/trytond/tests/test_modelsql.py
index 72d9f54e7d..4a2347dcaf 100644
--- a/trytond/trytond/tests/test_modelsql.py
+++ b/trytond/trytond/tests/test_modelsql.py
@@ -1251,6 +1251,27 @@ class ModelSQLTestCase(TestCase):
         self.assertEqual(Model.search(domain), [model_c, model_a])
         self.assertIn('UNION', str(Model.search(domain, query=True)))
 
+    @with_transaction()
+    def test_search_or_to_union_function_field(self):
+        pool = Pool()
+        Model = pool.get('test.modelsql.search.or2union')
+
+        model_a, model_b, model_c = Model.create([{
+                    'name': 'A',
+                    }, {
+                    'name': 'B',
+                    }, {
+                    'name': 'C',
+                    'targets': [
+                        ('create', [{'name': 'A'}]),
+                        ],
+                    },
+                ])
+
+        domain = [('rec_name', '=', 'A')]
+        self.assertEqual(Model.search(domain), [model_a, model_c])
+        self.assertIn('UNION', str(Model.search(domain, query=True)))
+
     @with_transaction()
     def test_search_limit(self):
         "Test searching with limit"