diff --git a/CHANGELOG.md b/CHANGELOG.md
index a74a565..f895ef1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -117,6 +117,9 @@ and this project adheres to
 
 ### Fixed
 
+- Fix nested includes being dropped for a resource that an earlier include
+  path already reached with a shallower include
+  ([#125](https://github.com/tobyzerner/json-api-server/issues/125))
 - `Context::filter()` and `filters()` now normalize the request's filters for
   the primary collection, so related resources no longer reject valid filters
 - Laravel: Reject cursors that can't be decoded instead of ignoring them and
diff --git a/src/Serializer.php b/src/Serializer.php
index 3c4bd88..3f04143 100644
--- a/src/Serializer.php
+++ b/src/Serializer.php
@@ -156,14 +156,13 @@ private function initializeResource(
     private function serializeFields(string $key, Context $context): void
     {
         foreach ($context->sparseFields($context->resource) as $field) {
-            if ($this->fieldProcessed($key, $field)) {
+            $include = $context->include[$field->name] ?? null;
+
+            if ($this->fieldProcessed($key, $field, $include)) {
                 continue;
             }
 
-            $fieldContext = $context->forSerializedField(
-                $field,
-                $context->include[$field->name] ?? null,
-            );
+            $fieldContext = $context->forSerializedField($field, $include);
 
             if (!$field->isVisible($fieldContext)) {
                 continue;
@@ -214,17 +213,54 @@ private function serializeLinks(string $key, Context $context): void
         }
     }
 
-    private function fieldProcessed(string $key, Field $field): bool
+    /**
+     * A resource can be reached through several include paths. A field that
+     * was already processed is processed again only if this path includes
+     * something the earlier paths did not, so its related resources get the
+     * deeper include.
+     */
+    private function fieldProcessed(string $key, Field $field, ?array $include): bool
     {
-        if (in_array($field, $this->processedFields[$key] ?? [], true)) {
-            return true;
+        // false marks a field processed without an include
+        $processed = $this->processedFields[$key][$field->name] ?? null;
+
+        if ($processed !== null) {
+            if (
+                $include === null
+                || $include === $processed
+                || $processed !== false && $this->includeCovers($processed, $include)
+            ) {
+                return true;
+            }
+
+            $include = $this->mergeInclude($processed ?: [], $include);
         }
 
-        $this->processedFields[$key][] = $field;
+        $this->processedFields[$key][$field->name] = $include ?? false;
 
         return false;
     }
 
+    private function includeCovers(array $processed, array $include): bool
+    {
+        foreach ($include as $name => $nested) {
+            if (!isset($processed[$name]) || !$this->includeCovers($processed[$name], $nested)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private function mergeInclude(array $processed, array $include): array
+    {
+        foreach ($include as $name => $nested) {
+            $processed[$name] = $this->mergeInclude($processed[$name] ?? [], $nested);
+        }
+
+        return $processed;
+    }
+
     private function resolveDeferred(): void
     {
         $i = 0;
diff --git a/tests/specification/InclusionOfRelatedResourcesTest.php b/tests/specification/InclusionOfRelatedResourcesTest.php
index eb59e17..88f22bb 100644
--- a/tests/specification/InclusionOfRelatedResourcesTest.php
+++ b/tests/specification/InclusionOfRelatedResourcesTest.php
@@ -378,4 +378,99 @@ public function test_relationship_inclusion_for_polymorphic_relationship()
             $response->getBody(),
         );
     }
+
+    public function test_deeper_include_on_resource_already_reached_through_shallower_path()
+    {
+        $image = (object) ['id' => '1'];
+        $user = (object) ['id' => '1', 'avatar' => $image];
+
+        $this->api->resource(new MockResource('images', models: [$image]));
+
+        $this->api->resource(
+            new MockResource(
+                'people',
+                models: [$user],
+                fields: [ToOne::make('avatar')->type('images')->includable()],
+            ),
+        );
+
+        $this->api->resource(
+            new MockResource(
+                'posts',
+                models: [(object) ['id' => '1', 'author' => $user, 'editor' => $user]],
+                endpoints: [Show::make()],
+                fields: [
+                    ToOne::make('author')->type('people')->includable(),
+                    ToOne::make('editor')->type('people')->includable(),
+                ],
+            ),
+        );
+
+        $response = $this->api->handle(
+            $this->buildRequest('GET', '/posts/1?include=author,editor.avatar'),
+        );
+
+        $this->assertEqualsCanonicalizing(
+            ['people:1', 'images:1'],
+            $this->includedKeys($response->getBody()),
+        );
+    }
+
+    public function test_sibling_includes_on_resource_reached_through_two_paths()
+    {
+        $image = (object) ['id' => '1'];
+        $banner = (object) ['id' => '2'];
+        $team = (object) ['id' => '1', 'logo' => $image, 'banner' => $banner];
+        $user = (object) ['id' => '1', 'team' => $team];
+
+        $this->api->resource(new MockResource('images', models: [$image, $banner]));
+
+        $this->api->resource(
+            new MockResource(
+                'teams',
+                models: [$team],
+                fields: [
+                    ToOne::make('logo')->type('images')->includable(),
+                    ToOne::make('banner')->type('images')->includable(),
+                ],
+            ),
+        );
+
+        $this->api->resource(
+            new MockResource(
+                'people',
+                models: [$user],
+                fields: [ToOne::make('team')->type('teams')->includable()],
+            ),
+        );
+
+        $this->api->resource(
+            new MockResource(
+                'posts',
+                models: [(object) ['id' => '1', 'author' => $user, 'editor' => $user]],
+                endpoints: [Show::make()],
+                fields: [
+                    ToOne::make('author')->type('people')->includable(),
+                    ToOne::make('editor')->type('people')->includable(),
+                ],
+            ),
+        );
+
+        $response = $this->api->handle(
+            $this->buildRequest('GET', '/posts/1?include=author.team.logo,editor.team.banner'),
+        );
+
+        $this->assertEqualsCanonicalizing(
+            ['people:1', 'teams:1', 'images:1', 'images:2'],
+            $this->includedKeys($response->getBody()),
+        );
+    }
+
+    private function includedKeys(string $body): array
+    {
+        return array_map(
+            fn($resource) => $resource['type'] . ':' . $resource['id'],
+            json_decode($body, true)['included'] ?? [],
+        );
+    }
 }