diff --git a/src/Illuminate/Http/Resources/JsonApi/Concerns/ResolvesJsonApiElements.php b/src/Illuminate/Http/Resources/JsonApi/Concerns/ResolvesJsonApiElements.php
index 67469fd9c656..5f5cc717d44e 100644
--- a/src/Illuminate/Http/Resources/JsonApi/Concerns/ResolvesJsonApiElements.php
+++ b/src/Illuminate/Http/Resources/JsonApi/Concerns/ResolvesJsonApiElements.php
@@ -235,8 +235,10 @@ protected static function resourceTypeFromModel(Model $model): string
 
         $morphMap = Relation::getMorphAlias($modelClassName);
 
-        return Str::of(
-            $morphMap !== $modelClassName ? $morphMap : class_basename($modelClassName)
-        )->snake()->pluralStudly();
+        if ($morphMap !== $modelClassName) {
+            return Str::of($morphMap)->pluralStudly();
+        }
+
+        return Str::of($modelClassName)->classBasename()->snake()->pluralStudly();
     }
 }
diff --git a/tests/Http/Resources/JsonApi/JsonApiResourceTest.php b/tests/Http/Resources/JsonApi/JsonApiResourceTest.php
index 9f3fc8a94d6f..6beb29009508 100644
--- a/tests/Http/Resources/JsonApi/JsonApiResourceTest.php
+++ b/tests/Http/Resources/JsonApi/JsonApiResourceTest.php
@@ -3,16 +3,40 @@
 namespace Illuminate\Tests\Http\Resources\JsonApi;
 
 use BadMethodCallException;
+use Illuminate\Container\Container;
+use Illuminate\Contracts\Routing\ResponseFactory as ResponseFactoryContract;
+use Illuminate\Contracts\View\Factory as ViewFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\Relation;
+use Illuminate\Http\Request;
 use Illuminate\Http\Resources\Json\JsonResource;
 use Illuminate\Http\Resources\JsonApi\JsonApiResource;
+use Illuminate\Routing\Redirector;
+use Illuminate\Routing\ResponseFactory;
+use Mockery as m;
 use PHPUnit\Framework\TestCase;
 
 class JsonApiResourceTest extends TestCase
 {
+    protected function setUp(): void
+    {
+        Relation::morphMap(['json-api-model' => JsonApiModel::class]);
+
+        $container = Container::setInstance(new Container);
+        $container->instance(ResponseFactoryContract::class, new ResponseFactory(
+            m::mock(ViewFactory::class),
+            m::mock(Redirector::class)
+        ));
+    }
+
     protected function tearDown(): void
     {
         JsonResource::flushState();
         JsonApiResource::flushState();
+        Relation::morphMap([], false);
+
+        Container::setInstance(null);
+        m::close();
     }
 
     public function testResponseWrapperIsHardCodedToData()
@@ -37,4 +61,54 @@ public function testUnableToUnsetWrapper()
 
         JsonApiResource::withoutWrapping();
     }
+
+    public function testResourceTypeIsPickedFromMorph()
+    {
+        $model = new JsonApiModel(['id' => 1, 'name' => 'User']);
+
+        $responseData = $this->fakeJsonApiResponseForModel($model)['data'];
+
+        $this->assertArrayHasKey('type', $responseData);
+        $this->assertSame('json-api-models', $responseData['type']);
+    }
+
+    public function testIncludedResourceDoesNotContainPrimaryKey()
+    {
+        $model = new JsonApiModel(['id' => 1, 'name' => 'User']);
+        $model->setRelation('manager', new JsonApiModel(['id' => 2, 'name' => 'Manager']));
+        $model->setRelation('deputy', new JsonApiModel(['id' => 2, 'email' => 'deputy@example.com']));
+
+        $responseData = $this->fakeJsonApiResponseForModel($model);
+        $this->assertArrayNotHasKey('id', $responseData['included'][0]['attributes']);
+    }
+
+    public function testIncludedMatchingResourceAttributesAreMerged()
+    {
+        $model = new JsonApiModel(['id' => 1, 'name' => 'User']);
+        $model->setRelation('manager', new JsonApiModel(['id' => 2, 'name' => 'Manager']));
+        $model->setRelation('deputy', new JsonApiModel(['id' => 2, 'email' => 'deputy@example.com']));
+
+        $responseData = $this->fakeJsonApiResponseForModel($model);
+
+        $this->assertEquals([
+            'id' => '2',
+            'type' => 'json-api-models',
+            'attributes' => [
+                'name' => 'Manager',
+                'email' => 'deputy@example.com',
+            ],
+        ], $responseData['included'][0]);
+    }
+
+    protected function fakeJsonApiResponseForModel(Model $model): array
+    {
+        return (new JsonApiResource($model))
+            ->toResponse(new Request)
+            ->getData(true);
+    }
+}
+
+class JsonApiModel extends Model
+{
+    protected $guarded = [];
 }