diff --git a/src/Illuminate/Database/Eloquent/Casts/AsArrayObject.php b/src/Illuminate/Database/Eloquent/Casts/AsArrayObject.php
index db9a21b461ba..b039fb29cfd6 100644
--- a/src/Illuminate/Database/Eloquent/Casts/AsArrayObject.php
+++ b/src/Illuminate/Database/Eloquent/Casts/AsArrayObject.php
@@ -19,7 +19,7 @@ public static function castUsing(array $arguments)
         {
             public function get($model, $key, $value, $attributes)
             {
-                return isset($attributes[$key]) ? new ArrayObject(json_decode($attributes[$key], true)) : null;
+                return $value ? new ArrayObject(json_decode($value, true)) : null;
             }
 
             public function set($model, $key, $value, $attributes)
diff --git a/src/Illuminate/Database/Eloquent/Casts/AsCollection.php b/src/Illuminate/Database/Eloquent/Casts/AsCollection.php
index 585b6cfc7012..7c989c1eb9a2 100644
--- a/src/Illuminate/Database/Eloquent/Casts/AsCollection.php
+++ b/src/Illuminate/Database/Eloquent/Casts/AsCollection.php
@@ -20,7 +20,7 @@ public static function castUsing(array $arguments)
         {
             public function get($model, $key, $value, $attributes)
             {
-                return isset($attributes[$key]) ? new Collection(json_decode($attributes[$key], true)) : null;
+                return $value ? new Collection(json_decode($value, true)) : null;
             }
 
             public function set($model, $key, $value, $attributes)
diff --git a/src/Illuminate/Database/Eloquent/Casts/AsEncryptedArrayObject.php b/src/Illuminate/Database/Eloquent/Casts/AsEncryptedArrayObject.php
index 5918bc1b2203..c54b678d6f3f 100644
--- a/src/Illuminate/Database/Eloquent/Casts/AsEncryptedArrayObject.php
+++ b/src/Illuminate/Database/Eloquent/Casts/AsEncryptedArrayObject.php
@@ -20,7 +20,7 @@ public static function castUsing(array $arguments)
         {
             public function get($model, $key, $value, $attributes)
             {
-                return new ArrayObject(json_decode(Crypt::decryptString($attributes[$key]), true));
+                return new ArrayObject(json_decode(Crypt::decryptString($value), true));
             }
 
             public function set($model, $key, $value, $attributes)
diff --git a/src/Illuminate/Database/Eloquent/Casts/AsEncryptedCollection.php b/src/Illuminate/Database/Eloquent/Casts/AsEncryptedCollection.php
index ad11b1787b38..bd61d7557a2b 100644
--- a/src/Illuminate/Database/Eloquent/Casts/AsEncryptedCollection.php
+++ b/src/Illuminate/Database/Eloquent/Casts/AsEncryptedCollection.php
@@ -21,7 +21,7 @@ public static function castUsing(array $arguments)
         {
             public function get($model, $key, $value, $attributes)
             {
-                return new Collection(json_decode(Crypt::decryptString($attributes[$key]), true));
+                return new Collection(json_decode(Crypt::decryptString($value), true));
             }
 
             public function set($model, $key, $value, $attributes)
diff --git a/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php b/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php
index 1e57c91004d8..b125baed4e46 100644
--- a/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php
+++ b/src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php
@@ -1658,6 +1658,17 @@ public function originalIsEquivalent($key)
         } elseif ($this->hasCast($key, static::$primitiveCastTypes)) {
             return $this->castAttribute($key, $attribute) ===
                 $this->castAttribute($key, $original);
+        } elseif ($this->isClassCastable($key)) {
+            $caster = $this->resolveCasterClass($key);
+
+            $original = $this->normalizeCastClassResponse($key, $caster->set(
+                $this,
+                $key,
+                $caster instanceof CastsInboundAttributes ? $original : $caster->get($this, $key, $original, $this->attributes),
+                $this->attributes
+            ));
+
+            return $attribute === $original[$key];
         }
 
         return is_numeric($attribute) && is_numeric($original)
diff --git a/tests/Database/DatabaseEloquentModelTest.php b/tests/Database/DatabaseEloquentModelTest.php
index a36bba4fe3eb..f5acc6a0673c 100755
--- a/tests/Database/DatabaseEloquentModelTest.php
+++ b/tests/Database/DatabaseEloquentModelTest.php
@@ -2,6 +2,7 @@
 
 namespace Illuminate\Tests\Database;
 
+use ArrayObject;
 use DateTime;
 use DateTimeImmutable;
 use DateTimeInterface;
@@ -13,6 +14,7 @@
 use Illuminate\Database\ConnectionResolverInterface;
 use Illuminate\Database\ConnectionResolverInterface as Resolver;
 use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Casts\AsArrayObject;
 use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Database\Eloquent\JsonEncodingException;
 use Illuminate\Database\Eloquent\MassAssignmentException;
@@ -155,6 +157,24 @@ public function testDirtyOnCastedObjects()
         $this->assertFalse($model->isDirty('collectionAttribute'));
     }
 
+    public function testDirtyOnCastedArrayObject()
+    {
+        $model = new EloquentModelCastingStub;
+        $model->setRawAttributes([
+            'arrayobjectAttribute' => '{"foo": "bar"}',
+        ]);
+        $model->syncOriginal();
+
+        $this->assertInstanceOf(ArrayObject::class, $model->arrayobjectAttribute);
+        $this->assertFalse($model->isDirty('arrayobjectAttribute'));
+
+        $model->arrayobjectAttribute = ['foo' => 'bar'];
+        $this->assertFalse($model->isDirty('arrayobjectAttribute'));
+
+        $model->arrayobjectAttribute = ['foo' => 'baz'];
+        $this->assertTrue($model->isDirty('arrayobjectAttribute'));
+    }
+
     public function testCleanAttributes()
     {
         $model = new EloquentModelStub(['foo' => '1', 'bar' => 2, 'baz' => 3]);
@@ -2570,6 +2590,7 @@ class EloquentModelCastingStub extends Model
         'dateAttribute' => 'date',
         'datetimeAttribute' => 'datetime',
         'timestampAttribute' => 'timestamp',
+        'arrayobjectAttribute' => AsArrayObject::class,
     ];
 
     public function jsonAttributeValue()