diff --git a/django/contrib/postgres/lookups.py b/django/contrib/postgres/lookups.py
index 53a62eacd1..466b8cdf56 100644
--- a/django/contrib/postgres/lookups.py
+++ b/django/contrib/postgres/lookups.py
@@ -8,7 +8,7 @@ class PostgresSimpleLookup(Lookup):
     def as_sql(self, qn, connection):
         lhs, lhs_params = self.process_lhs(qn, connection)
         rhs, rhs_params = self.process_rhs(qn, connection)
-        params = lhs_params + rhs_params
+        params = tuple(lhs_params) + tuple(rhs_params)
         return '%s %s %s' % (lhs, self.operator, rhs), params
 
 
diff --git a/docs/releases/1.11.26.txt b/docs/releases/1.11.26.txt
index a0c39b4168..1a54b47e1b 100644
--- a/docs/releases/1.11.26.txt
+++ b/docs/releases/1.11.26.txt
@@ -9,4 +9,7 @@ Django 1.11.26 fixes a regression in 1.11.25.
 Bugfixes
 ========
 
-* ...
+* Fixed a crash when using a ``contains``, ``contained_by``, ``has_key``,
+  ``has_keys``, or ``has_any_keys`` lookup on
+  :class:`~django.contrib.postgres.fields.JSONField`, if the right or left hand
+  side of an expression is a key transform (:ticket:`30826`).
diff --git a/tests/postgres_tests/test_json.py b/tests/postgres_tests/test_json.py
index b8b5dd481f..faefcd18a3 100644
--- a/tests/postgres_tests/test_json.py
+++ b/tests/postgres_tests/test_json.py
@@ -21,7 +21,9 @@ from .models import JSONModel
 try:
     from django.contrib.postgres import forms
     from django.contrib.postgres.fields import JSONField
-    from django.contrib.postgres.fields.jsonb import KeyTransform
+    from django.contrib.postgres.fields.jsonb import (
+        KeyTextTransform, KeyTransform
+    )
 except ImportError:
     pass
 
@@ -130,7 +132,12 @@ class TestQuerying(PostgreSQLTestCase):
                 'k': True,
                 'l': False,
             }),
-            JSONModel.objects.create(field={'foo': 'bar'}),
+            JSONModel.objects.create(field={
+                'foo': 'bar',
+                'baz': {'a': 'b', 'c': 'd'},
+                'bar': ['foo', 'bar'],
+                'bax': {'foo': 'bar'},
+            }),
         ]
 
     def test_exact(self):
@@ -305,6 +312,25 @@ class TestQuerying(PostgreSQLTestCase):
             queries[0]['sql'],
         )
 
+    def test_lookups_with_key_transform(self):
+        tests = (
+            ('field__d__contains', 'e'),
+            ('field__baz__contained_by', {'a': 'b', 'c': 'd', 'e': 'f'}),
+            ('field__baz__has_key', 'c'),
+            ('field__baz__has_keys', ['a', 'c']),
+            ('field__baz__has_any_keys', ['a', 'x']),
+            ('field__contains', KeyTransform('bax', 'field')),
+            (
+                'field__contained_by',
+                KeyTransform('x', RawSQL('%s::jsonb', ['{"x": {"a": "b", "c": 1, "d": "e"}}'])),
+            ),
+            ('field__has_key', KeyTextTransform('foo', 'field')),
+        )
+        for lookup, value in tests:
+            self.assertTrue(JSONModel.objects.filter(
+                **{lookup: value}
+            ).exists())
+
 
 @skipUnlessDBFeature('has_jsonb_datatype')
 class TestSerialization(PostgreSQLTestCase):