src/IncludeResolver.php                  |  5 ++++-
 src/JsonApiResource/EntityCollection.php | 27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/IncludeResolver.php b/src/IncludeResolver.php
index 25ccfd1..5fc259a 100644
--- a/src/IncludeResolver.php
+++ b/src/IncludeResolver.php
@@ -58,7 +58,10 @@ class IncludeResolver {
     // Map a single entity into an EntityCollection.
     $entity_collection = $data instanceof EntityInterface ? new EntityCollection([$data], 1) : $data;
     $include_tree = static::toIncludeTree($base_resource_type, $include_parameter, $related_field);
-    return EntityCollection::deduplicate($this->resolveIncludeTree($include_tree, $entity_collection));
+    $result = EntityCollection::deduplicate($this->resolveIncludeTree($include_tree, $entity_collection));
+    return $related_field !== NULL && $data instanceof EntityInterface
+      ? EntityCollection::without($result, new EntityCollection($data->get($related_field)->referencedEntities()))
+      : $result;
   }
 
   /**
diff --git a/src/JsonApiResource/EntityCollection.php b/src/JsonApiResource/EntityCollection.php
index dd7504e..0c1b820 100644
--- a/src/JsonApiResource/EntityCollection.php
+++ b/src/JsonApiResource/EntityCollection.php
@@ -186,4 +186,31 @@ class EntityCollection implements \IteratorAggregate, \Countable {
     return new static(array_values($deduplicated));
   }
 
+  /**
+   * Returns a new EntityCollection without the specified needles.
+   *
+   * @param \Drupal\jsonapi\JsonApiResource\EntityCollection $collection
+   *   The EntityCollection to filter.
+   * @param \Drupal\jsonapi\JsonApiResource\EntityCollection $needles
+   *   The needles to filter away.
+   *
+   * @return \Drupal\jsonapi\JsonApiResource\EntityCollection
+   *   A new EntityCollection object, containing a subset of $collection.
+   */
+  public static function without(EntityCollection $collection, EntityCollection $needles) {
+    if (empty($needles)) {
+      return $collection;
+    }
+
+    $resource_identifier_needles = array_map([ResourceIdentifier::class, 'fromEntity'], $needles->toArray());
+    $without = [];
+    foreach ($collection->toArray() as $resource) {
+      $resource_identifier = ResourceIdentifier::fromEntity($resource);
+      if (empty(array_uintersect([$resource_identifier], $resource_identifier_needles, [ResourceIdentifier::class, 'compare']))) {
+        $without[] = $resource;
+      }
+    }
+    return new static($without);
+  }
+
 }