diff --git a/src/Query/Builder.php b/src/Query/Builder.php
index 2270466..f446853 100644
--- a/src/Query/Builder.php
+++ b/src/Query/Builder.php
@@ -33,4 +33,22 @@ public function useWritePdo()
 
         return $this;
     }
+
+    /**
+     * Add a subselect expression to the query.
+     *
+     * @param  \Closure|$this|string  $query
+     * @param  string  $as
+     * @return $this
+     *
+     * @throws \InvalidArgumentException
+     */
+    public function selectSub($query, $as)
+    {
+        if (get_class($query) == self::class) {
+            $this->appendCacheTags($query->getCacheTags() ?? []);
+        }
+
+        return parent::selectSub($query, $as);
+    }
 }
diff --git a/src/Traits/QueryCacheModule.php b/src/Traits/QueryCacheModule.php
index 738e8f2..53c58c0 100644
--- a/src/Traits/QueryCacheModule.php
+++ b/src/Traits/QueryCacheModule.php
@@ -272,6 +272,19 @@ public function cacheTags(array $cacheTags = [])
         return $this;
     }
 
+    /**
+     * Append tags to the cache.
+     *
+     * @param  array  $cacheTags
+     * @return \Rennokki\QueryCache\Query\Builder
+     */
+    public function appendCacheTags(array $cacheTags = [])
+    {
+        $this->cacheTags = array_unique(array_merge($this->cacheTags ?? [], $cacheTags));
+
+        return $this;
+    }
+
     /**
      * Use a specific cache driver.
      *
diff --git a/tests/MethodsTest.php b/tests/MethodsTest.php
index 75ee440..1bd6cea 100644
--- a/tests/MethodsTest.php
+++ b/tests/MethodsTest.php
@@ -6,6 +6,7 @@
 use Rennokki\QueryCache\Test\Models\Book;
 use Rennokki\QueryCache\Test\Models\Kid;
 use Rennokki\QueryCache\Test\Models\Post;
+use Rennokki\QueryCache\Test\Models\User;
 
 class MethodsTest extends TestCase
 {
@@ -123,4 +124,50 @@ public function test_hashed_key()
 
         $this->assertNotNull($cache);
     }
+
+    public function test_append_cache_tags()
+    {
+        $post = factory(Post::class)->create();
+        $storedPost = Post::cacheFor(now()->addHours(1))->appendCacheTags(['test'])->first();
+
+        $cache = $this->getCacheWithTags('leqc:sqlitegetselect * from "posts" limit 1a:0:{}');
+
+        // The caches that do not support tagging should
+        // cache the query either way.
+        $this->driverSupportsTags()
+            ? $this->assertNull($cache)
+            : $this->assertNotNull($cache);
+
+        $cache = $this->getCacheWithTags('leqc:sqlitegetselect * from "posts" limit 1a:0:{}', ['test']);
+        $this->assertNotNull($cache);
+    }
+
+    public function test_multiple_append_cache_tags()
+    {
+        $post = factory(Post::class)->create();
+        $storedPostQuery = Post::cacheFor(now()->addHours(1))->appendCacheTags(['test'])->appendCacheTags(['test2']);
+
+        $this->assertEquals($storedPostQuery->getQuery()->getCacheTags(), ['test', 'test2']);
+    }
+
+    public function test_append_cache_tags_with_sub_query()
+    {
+        $user = factory(User::class)->create();
+        factory(Post::class)->createMany([
+            ['user_id' => $user->id, 'name' => 'Post 1 on topic 1'],
+            ['user_id' => $user->id, 'name' => 'Post 2 on topic 1'],
+            ['user_id' => $user->id, 'name' => 'Post 3 on topic 2'],
+        ]);
+
+        $userAndPosts = User::cacheFor(now()->addHours(1))
+            ->withCount([
+                'posts' => function ($query) {
+                    $query->appendCacheTags(['posts'])
+                        ->where('name', 'like', '%topic 1%');
+                },
+            ])
+            ->appendCacheTags(['user']);
+
+        $this->assertEquals($userAndPosts->getQuery()->getCacheTags(), ['posts', 'user']);
+    }
 }
diff --git a/tests/Models/User.php b/tests/Models/User.php
index dac6955..935252f 100644
--- a/tests/Models/User.php
+++ b/tests/Models/User.php
@@ -3,9 +3,12 @@
 namespace Rennokki\QueryCache\Test\Models;
 
 use Illuminate\Foundation\Auth\User as Authenticatable;
+use Rennokki\QueryCache\Traits\QueryCacheable;
 
 class User extends Authenticatable
 {
+    use QueryCacheable;
+
     protected $fillable = [
         'name', 'email', 'password',
     ];
@@ -20,4 +23,9 @@ protected function getCacheBaseTags(): array
             //
         ];
     }
+
+    public function posts()
+    {
+        return $this->hasMany(Post::class);
+    }
 }
diff --git a/tests/database/migrations/2018_07_14_183253_posts.php b/tests/database/migrations/2018_07_14_183253_posts.php
index ddcb62d..85fb75c 100644
--- a/tests/database/migrations/2018_07_14_183253_posts.php
+++ b/tests/database/migrations/2018_07_14_183253_posts.php
@@ -15,6 +15,7 @@ public function up()
     {
         Schema::create('posts', function (Blueprint $table) {
             $table->increments('id');
+            $table->unsignedBigInteger('user_id')->nullable();
             $table->string('name');
             $table->timestamps();
         });