From cc048c62420ebb174de1004c2e8340e6edd88683 Mon Sep 17 00:00:00 2001
From: Jason Varga <jason@pixelfear.com>
Date: Fri, 5 Dec 2025 12:08:26 -0500
Subject: [PATCH 1/2] use a placeholder for nulls

---
 src/Stache/Query/Builder.php | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Stache/Query/Builder.php b/src/Stache/Query/Builder.php
index f1e89825c36..31294404634 100644
--- a/src/Stache/Query/Builder.php
+++ b/src/Stache/Query/Builder.php
@@ -157,19 +157,19 @@ protected function filterWhereBasic($values, $where)
 
     protected function filterWhereIn($values, $where)
     {
-        $lookup = array_flip($where['values']);
+        $lookup = array_flip(array_map(fn ($v) => $v ?? '__NULL__', $where['values']));
 
         return $values->filter(
-            fn ($value) => isset($lookup[$value])
+            fn ($value) => isset($lookup[$value ?? '__NULL__'])
         );
     }
 
     protected function filterWhereNotIn($values, $where)
     {
-        $lookup = array_flip($where['values']);
+        $lookup = array_flip(array_map(fn ($v) => $v ?? '__NULL__', $where['values']));
 
         return $values->filter(
-            fn ($value) => ! isset($lookup[$value])
+            fn ($value) => ! isset($lookup[$value ?? '__NULL__'])
         );
     }
 

From d2118cc9755d929cabb2231a451f003ae730099e Mon Sep 17 00:00:00 2001
From: Jason Varga <jason@pixelfear.com>
Date: Mon, 8 Dec 2025 10:00:57 -0500
Subject: [PATCH 2/2] add test

Co-authored-by: Beau Hastings <beau@saweet.net>
---
 tests/Data/Entries/EntryQueryBuilderTest.php | 30 ++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/tests/Data/Entries/EntryQueryBuilderTest.php b/tests/Data/Entries/EntryQueryBuilderTest.php
index 22950c866a2..8346a2a1695 100644
--- a/tests/Data/Entries/EntryQueryBuilderTest.php
+++ b/tests/Data/Entries/EntryQueryBuilderTest.php
@@ -91,6 +91,36 @@ public function entries_are_found_using_or_where_not_in()
         $this->assertEquals(['Post 3', 'Post 4'], $entries->map->title->all());
     }
 
+    #[Test]
+    public function entries_are_found_using_where_in_with_null()
+    {
+        EntryFactory::id('1')->slug('post-1')->collection('posts')->data(['title' => 'Post 1', 'category' => 'news'])->create();
+        EntryFactory::id('2')->slug('post-2')->collection('posts')->data(['title' => 'Post 2', 'category' => 'blog'])->create();
+        EntryFactory::id('3')->slug('post-3')->collection('posts')->data(['title' => 'Post 3'])->create(); // category is null
+        EntryFactory::id('4')->slug('post-4')->collection('posts')->data(['title' => 'Post 4', 'category' => 'news'])->create();
+        EntryFactory::id('5')->slug('post-5')->collection('posts')->data(['title' => 'Post 5'])->create(); // category is null
+
+        $entries = Entry::query()->whereIn('category', ['news', null])->get();
+
+        $this->assertCount(4, $entries);
+        $this->assertEquals(['Post 1', 'Post 3', 'Post 4', 'Post 5'], $entries->map->title->all());
+    }
+
+    #[Test]
+    public function entries_are_found_using_where_not_in_with_null()
+    {
+        EntryFactory::id('1')->slug('post-1')->collection('posts')->data(['title' => 'Post 1', 'category' => 'news'])->create();
+        EntryFactory::id('2')->slug('post-2')->collection('posts')->data(['title' => 'Post 2', 'category' => 'blog'])->create();
+        EntryFactory::id('3')->slug('post-3')->collection('posts')->data(['title' => 'Post 3'])->create(); // category is null
+        EntryFactory::id('4')->slug('post-4')->collection('posts')->data(['title' => 'Post 4', 'category' => 'news'])->create();
+        EntryFactory::id('5')->slug('post-5')->collection('posts')->data(['title' => 'Post 5'])->create(); // category is null
+
+        $entries = Entry::query()->whereNotIn('category', ['news', null])->get();
+
+        $this->assertCount(1, $entries);
+        $this->assertEquals(['Post 2'], $entries->map->title->all());
+    }
+
     #[Test]
     public function entries_are_found_using_where_date()
     {