diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52fbd95..362e1a2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,14 @@ All notable changes to this project will be documented in this file. This projec
 
 ## Unreleased
 
+## [4.1.0] - 2024-06-26
+
+### Fixed
+
+- [#17](https://github.com/laravel-json-api/core/pull/17) Fix incorrect `self` link in related resource responses, and
+  remove `related` link that should not exist. This has been incorrect for some time, but is definitely what
+  the [spec defines here.](https://jsonapi.org/format/1.0/#document-top-level)
+
 ## [4.0.0] - 2024-03-12
 
 ### Changed
diff --git a/src/Core/Document/Links.php b/src/Core/Document/Links.php
index 1d07f50..fdbd363 100644
--- a/src/Core/Document/Links.php
+++ b/src/Core/Document/Links.php
@@ -191,6 +191,25 @@ public function hasRelated(): bool
         return $this->has('related');
     }
 
+    /**
+     * @return $this
+     */
+    public function relatedAsSelf(): self
+    {
+        $related = $this->getRelated();
+
+        if ($related) {
+            $this->push(new Link(
+                key: 'self',
+                href: $related->href(),
+                meta: $related->meta(),
+            ));
+            return $this->forget('related');
+        }
+
+        return $this->forget('self');
+    }
+
     /**
      * Push links into the collection.
      *
diff --git a/src/Core/Responses/Internal/RelatedResourceCollectionResponse.php b/src/Core/Responses/Internal/RelatedResourceCollectionResponse.php
index db33285..14e9b0b 100644
--- a/src/Core/Responses/Internal/RelatedResourceCollectionResponse.php
+++ b/src/Core/Responses/Internal/RelatedResourceCollectionResponse.php
@@ -14,6 +14,7 @@
 use Illuminate\Contracts\Support\Responsable;
 use Illuminate\Http\Request;
 use Illuminate\Http\Response;
+use LaravelJsonApi\Core\Document\Links;
 use LaravelJsonApi\Core\Resources\JsonApiResource;
 use LaravelJsonApi\Core\Responses\Concerns\HasEncodingParameters;
 use LaravelJsonApi\Core\Responses\Concerns\HasRelationship;
@@ -68,4 +69,17 @@ public function toResponse($request)
             $this->headers()
         );
     }
+
+    /**
+     * Get all links.
+     *
+     * @return Links
+     */
+    private function allLinks(): Links
+    {
+        return $this
+            ->linksForRelationship()
+            ->relatedAsSelf()
+            ->merge($this->links());
+    }
 }
diff --git a/src/Core/Responses/Internal/RelatedResourceResponse.php b/src/Core/Responses/Internal/RelatedResourceResponse.php
index d03b896..0b9ea61 100644
--- a/src/Core/Responses/Internal/RelatedResourceResponse.php
+++ b/src/Core/Responses/Internal/RelatedResourceResponse.php
@@ -14,6 +14,7 @@
 use Illuminate\Contracts\Support\Responsable;
 use Illuminate\Http\Request;
 use Illuminate\Http\Response;
+use LaravelJsonApi\Core\Document\Links;
 use LaravelJsonApi\Core\Resources\JsonApiResource;
 use LaravelJsonApi\Core\Responses\Concerns\HasEncodingParameters;
 use LaravelJsonApi\Core\Responses\Concerns\HasRelationship;
@@ -52,6 +53,7 @@ public function toResponse($request)
     {
         $encoder = $this->server()->encoder();
 
+        $links = $this->allLinks();
         $document = $encoder
             ->withRequest($request)
             ->withIncludePaths($this->includePaths($request))
@@ -68,4 +70,17 @@ public function toResponse($request)
             $this->headers()
         );
     }
+
+    /**
+     * Get all links.
+     *
+     * @return Links
+     */
+    private function allLinks(): Links
+    {
+        return $this
+            ->linksForRelationship()
+            ->relatedAsSelf()
+            ->merge($this->links());
+    }
 }
diff --git a/src/Core/Schema/Concerns/MatchesIds.php b/src/Core/Schema/Concerns/MatchesIds.php
index 90f6346..ed40a34 100644
--- a/src/Core/Schema/Concerns/MatchesIds.php
+++ b/src/Core/Schema/Concerns/MatchesIds.php
@@ -13,7 +13,6 @@
 
 trait MatchesIds
 {
-
     /**
      * @var string
      */
@@ -39,7 +38,7 @@ public function pattern(): string
      *
      * @return $this
      */
-    public function uuid(): self
+    public function uuid(): static
     {
         return $this->matchAs('[\da-f]{8}-[\da-f]{4}-[\da-f]{4}-[\da-f]{4}-[\da-f]{12}');
     }
@@ -49,7 +48,7 @@ public function uuid(): self
      *
      * @return $this
      */
-    public function ulid(): self
+    public function ulid(): static
     {
         return $this->matchAs('[0-7][0-9a-hjkmnp-tv-zA-HJKMNP-TV-Z]{25}');
     }
@@ -60,7 +59,7 @@ public function ulid(): self
      * @param string $pattern
      * @return $this
      */
-    public function matchAs(string $pattern): self
+    public function matchAs(string $pattern): static
     {
         $this->pattern = $pattern;
 
@@ -72,7 +71,7 @@ public function matchAs(string $pattern): self
      *
      * @return $this
      */
-    public function matchCase(): self
+    public function matchCase(): static
     {
         $this->flags = 'D';
 
diff --git a/tests/Unit/Document/LinksTest.php b/tests/Unit/Document/LinksTest.php
index 0fe8ead..c23073d 100644
--- a/tests/Unit/Document/LinksTest.php
+++ b/tests/Unit/Document/LinksTest.php
@@ -294,4 +294,23 @@ public function testOffsetUnset(): void
 
         $this->assertSame(['related' => $related], $links->all());
     }
+
+    public function testRelatedToSelfWithRelated(): void
+    {
+        $links = new Links(
+            new Link('self', '/api/posts/1/relationships/author'),
+            new Link('related', '/api/posts/1/author'),
+        );
+
+        $this->assertEquals(['self' => new Link('self', '/api/posts/1/author'),], $links->relatedAsSelf()->all());
+    }
+
+    public function testRelatedToSelfWithoutRelated(): void
+    {
+        $links = new Links(
+            new Link('self', '/api/posts/1/relationships/author'),
+        );
+
+        $this->assertTrue($links->relatedAsSelf()->isEmpty());
+    }
 }
diff --git a/tests/Unit/Schema/Concerns/MatchesIdsTest.php b/tests/Unit/Schema/Concerns/MatchesIdsTest.php
new file mode 100644
index 0000000..2628ed5
--- /dev/null
+++ b/tests/Unit/Schema/Concerns/MatchesIdsTest.php
@@ -0,0 +1,82 @@
+<?php
+/*
+ * Copyright 2024 Cloud Creativity Limited
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ */
+
+declare(strict_types=1);
+
+namespace LaravelJsonApi\Core\Tests\Unit\Schema\Concerns;
+
+use LaravelJsonApi\Core\Schema\Concerns\MatchesIds;
+use PHPUnit\Framework\TestCase;
+
+class MatchesIdsTest extends TestCase
+{
+    /**
+     * @return void
+     */
+    public function testItIsNumeric(): void
+    {
+        $id = new class () {
+            use MatchesIds;
+        };
+
+        $this->assertSame('[0-9]+', $id->pattern());
+        $this->assertTrue($id->match('1234'));
+        $this->assertFalse($id->match('123A45'));
+    }
+
+    /**
+     * @return void
+     */
+    public function testItIsUuid(): void
+    {
+        $id = new class () {
+            use MatchesIds;
+        };
+
+        $this->assertSame($id, $id->uuid());
+        $this->assertSame('[\da-f]{8}-[\da-f]{4}-[\da-f]{4}-[\da-f]{4}-[\da-f]{12}', $id->pattern());
+        $this->assertTrue($id->match('fca1509e-9178-45fd-8a2b-ae819d34f7e6'));
+        $this->assertFalse($id->match('fca1509e917845fd8a2bae819d34f7e6'));
+    }
+
+    /**
+     * @return void
+     */
+    public function testItIsUlid(): void
+    {
+        $id = new class () {
+            use MatchesIds;
+        };
+
+        $this->assertSame($id, $id->ulid());
+        $this->assertSame('[0-7][0-9a-hjkmnp-tv-zA-HJKMNP-TV-Z]{25}', $id->pattern());
+        $this->assertTrue($id->match('01HT4PA8AZC8Q30ZGC5PEWZP0E'));
+        $this->assertFalse($id->match('01HT4PA8AZC8Q30ZGC5PEWZP0'));
+    }
+
+    /**
+     * @return void
+     */
+    public function testItIsCustom(): void
+    {
+        $id = new class () {
+            use MatchesIds;
+        };
+
+        $this->assertSame($id, $id->matchAs('[A-D]+'));
+        $this->assertSame('[A-D]+', $id->pattern());
+        $this->assertTrue($id->match('abcd'));
+        $this->assertTrue($id->match('ABCD'));
+        $this->assertFalse($id->match('abcde'));
+
+        $this->assertSame($id, $id->matchCase());
+        $this->assertTrue($id->match('ABCD'));
+        $this->assertFalse($id->match('abcd'));
+    }
+}
\ No newline at end of file