diff --git a/package.json b/package.json
index 39f0436..6a74f9e 100644
--- a/package.json
+++ b/package.json
@@ -42,6 +42,6 @@
     "@types/type-check": "^0.3.27",
     "jasmine": "^2.5.3",
     "tslint": "^4.3.1",
-    "typescript": "^2.1.5"
+    "typescript": "^4.0.0"
   }
 }
diff --git a/spec/deserializer-spec.ts b/spec/deserializer-spec.ts
index 73c18eb..29718d2 100644
--- a/spec/deserializer-spec.ts
+++ b/spec/deserializer-spec.ts
@@ -82,17 +82,19 @@ describe('deserialize', () => {
 
     let expected = [
       {
+        'type': 'articles',
         'id': '1',
         'title': 'JSON API paints my bikeshed!',
         'author': {
+          'type': 'people',
           'id': '9',
           'first-name': 'Dan',
           'last-name': 'Gebhardt',
           'twitter': 'dgeb'
         },
         'comments': [
-          { 'id': '5', 'body': 'First!' },
-          { 'id': '12', 'body': 'I like XML better' }
+          { 'type': 'comments', 'id': '5', 'body': 'First!' },
+          { 'type': 'comments', 'id': '12', 'body': 'I like XML better' }
         ]
       }
     ];
@@ -124,8 +126,8 @@ describe('deserialize', () => {
     let result: any = deserialize(document);
 
     let expected = [
-      { id: '1', name: 'John', friend: { id: '2', name: 'Carl', dog: { id: '3', name: 'Bobby' } } },
-      { id: '2', name: 'Carl', dog: { id: '3', name: 'Bobby' } }
+      { type: 'people', id: '1', name: 'John', friend: { type: 'people', id: '2', name: 'Carl', dog: { type: 'dogs', id: '3', name: 'Bobby' } } },
+      { type: 'people', id: '2', name: 'Carl', dog: { type: 'dogs', id: '3', name: 'Bobby' } }
     ];
 
     expect(matches(expected)(result)).toBe(true);
diff --git a/src/index.ts b/src/index.ts
index eb55960..88197e1 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -29,7 +29,7 @@ function denormalize(resources: Multiple<Resource>, relations: RelationsHash): a
 }
 
 function processResource(res: Resource, relHash: RelationsHash): Serialization {
-  let { id, attributes, relationships } = res;
+  let { id, type, attributes, relationships } = res;
 
   let rels: Multiple<any> = mapValues(relationships, (rel: RelationshipObj): any =>
     fmapMultiple(rel.data, (relId: ResourceId): any => {
@@ -38,7 +38,7 @@ function processResource(res: Resource, relHash: RelationsHash): Serialization {
     })
   );
 
-  return assign({}, attributes, { id }, rels);
+  return assign({}, attributes, { type, id }, rels);
 }
 
 function findRelation(rel: ResourceId, relations: RelationsHash): Resource | undefined {