diff --git a/trytond/tests/test_tools.py b/trytond/tests/test_tools.py
index 60005efc3b..c6bb78c8be 100644
--- a/trytond/tests/test_tools.py
+++ b/trytond/tests/test_tools.py
@@ -118,6 +118,8 @@ class ToolsTestCase(unittest.TestCase):
                 ['OR', clause, ['AND', clause, ['OR', clause, clause]]]),
             (['OR', [clause]], ['OR', ['AND', clause]]),
             ([], []),
+            (['OR', clause, []], ['OR', clause, []]),
+            (['AND', clause, []], ['AND', clause, []]),
         )
         for i, j in tests:
             self.assertEqual(reduce_domain(i), j,
diff --git a/trytond/tools/misc.py b/trytond/tools/misc.py
index fc41cbdcf7..c20e264a95 100644
--- a/trytond/tools/misc.py
+++ b/trytond/tools/misc.py
@@ -446,4 +446,6 @@ def reduce_domain(domain):
                 result.extend(sub_domain[1:])
             else:
                 result.append(sub_domain)
+        else:
+            result.append(arg)
     return result