diff --git a/tests/postgres_tests/test_constraints.py b/tests/postgres_tests/test_constraints.py
index 2cc3de5f4d..96b5d39092 100644
--- a/tests/postgres_tests/test_constraints.py
+++ b/tests/postgres_tests/test_constraints.py
@@ -309,7 +309,7 @@ class ExclusionConstraintTests(PostgreSQLTestCase):
 
     def test_invalid_expressions(self):
         msg = "The expressions must be a list of 2-tuples."
-        for expressions in (["foo"], ["foo"], [("foo_1", "foo_2", "foo_3")]):
+        for expressions in (["foo"], [("foo",)], [("foo_1", "foo_2", "foo_3")]):
             with self.subTest(expressions), self.assertRaisesMessage(ValueError, msg):
                 ExclusionConstraint(
                     index_type="GIST",