diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7bee410e..6f850144 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Attachment factories now properly use the `Attachment_Factory` class.
 - Ensure that the `delete()` method of the HTTP Client doesn't set a body by default.
 - Ensure that `with_terms()` can support an array of term slugs when passed with a
   taxonomy index.
diff --git a/src/mantle/database/factory/class-attachment-factory.php b/src/mantle/database/factory/class-attachment-factory.php
index 28218504..7b87dfe3 100644
--- a/src/mantle/database/factory/class-attachment-factory.php
+++ b/src/mantle/database/factory/class-attachment-factory.php
@@ -75,6 +75,8 @@ public function with_image( string $file = null, int $parent = 0, int $width = 6
 			if ( ! $file ) {
 				$file = $generated_images[ $hash ] = $this->generate_image( $width, $height );
 			}
+		} elseif ( ! file_exists( $file ) ) {
+			throw new RuntimeException( "File {$file} does not exist." );
 		}
 
 		if ( empty( $file ) ) {
diff --git a/src/mantle/database/factory/class-post-factory.php b/src/mantle/database/factory/class-post-factory.php
index 6f1b41ad..ff9247ba 100644
--- a/src/mantle/database/factory/class-post-factory.php
+++ b/src/mantle/database/factory/class-post-factory.php
@@ -10,6 +10,7 @@
 use Carbon\Carbon;
 use Closure;
 use Faker\Generator;
+use Mantle\Database\Model\Attachment;
 use Mantle\Database\Model\Post;
 use WP_Post;
 
@@ -145,7 +146,7 @@ function ( array $args, Closure $next ) use ( $file, $width, $height, $recycle )
 				update_post_meta(
 					$post->ID,
 					'_thumbnail_id',
-					( new Attachment_Factory( $this->faker ) )->with_image(
+					Attachment::factory()->with_image(
 						file: $file,
 						width: $width,
 						parent: $post->ID,
diff --git a/src/mantle/database/factory/concerns/trait-resolves-factories.php b/src/mantle/database/factory/concerns/trait-resolves-factories.php
index 3ccf0400..8cd93d0f 100644
--- a/src/mantle/database/factory/concerns/trait-resolves-factories.php
+++ b/src/mantle/database/factory/concerns/trait-resolves-factories.php
@@ -125,8 +125,10 @@ public static function default_factory_name( string $model_name ): string {
 		}
 
 		// Handle one-off models.
-		if ( Model\Site::class === $parent_class ) {
+		if ( in_array( Model\Site::class, [ $model_name, $parent_class ], true ) ) {
 			return Factory\Blog_Factory::class;
+		} elseif ( in_array( Model\Attachment::class, [ $model_name, $parent_class ], true ) ) {
+			return Factory\Attachment_Factory::class;
 		}
 
 		$parent_class = Str::after_last( $parent_class, '\\' );
diff --git a/src/mantle/database/model/class-attachment.php b/src/mantle/database/model/class-attachment.php
index 4dbeddbe..d2d4d06d 100644
--- a/src/mantle/database/model/class-attachment.php
+++ b/src/mantle/database/model/class-attachment.php
@@ -12,7 +12,7 @@
 /**
  * Attachment Model
  *
- * @method static \Mantle\Database\Factory\Post_Factory<static, \WP_Post, static> factory( array|callable|null $state = null )
+ * @method static \Mantle\Database\Factory\Attachment_Factory<static, \WP_Post, static> factory( array|callable|null $state = null )
  */
 class Attachment extends Post {
 	/**
diff --git a/tests/Database/Factory/FactoryTest.php b/tests/Database/Factory/FactoryTest.php
index 41772ed8..61e90aed 100644
--- a/tests/Database/Factory/FactoryTest.php
+++ b/tests/Database/Factory/FactoryTest.php
@@ -70,7 +70,7 @@ public function test_resolve_default( string $model, string $expected ) {
 
 	public static function factory_resolve_default(): array {
 		return [
-			Model\Attachment::class => [ Model\Attachment::class, Factory\Post_Factory::class ],
+			Model\Attachment::class => [ Model\Attachment::class, Factory\Attachment_Factory::class ],
 			Model\Post::class => [ Model\Post::class, Factory\Post_Factory::class ],
 			Model\Term::class => [ Model\Term::class, Factory\Term_Factory::class ],
 			Model\User::class => [ Model\User::class, Factory\User_Factory::class ],