diff --git a/CHANGELOG.md b/CHANGELOG.md
index d776f78..34edc0a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.4.3
+
+* Fix "Document Validation" API - returning nullable type
+
 ## 0.4.2
 
 * Update API client - Document Validation
diff --git a/lib/src/autogram_service.dart b/lib/src/autogram_service.dart
index 4f635ee..8e62f6b 100644
--- a/lib/src/autogram_service.dart
+++ b/lib/src/autogram_service.dart
@@ -61,7 +61,7 @@ class AutogramService implements IAutogramService {
   }
 
   @override
-  Future<DocumentValidationResponseBody> getDocumentValidation(
+  Future<DocumentValidationResponseBody?> getDocumentValidation(
     String documentId,
   ) {
     return _autogram.documentsGuidValidateGet(guid: documentId).then(unwrap);
diff --git a/lib/src/iautogram_service.dart b/lib/src/iautogram_service.dart
index eafd14e..fd77b9c 100644
--- a/lib/src/iautogram_service.dart
+++ b/lib/src/iautogram_service.dart
@@ -32,8 +32,8 @@ abstract class IAutogramService {
 
   /// Requests a signature validation report of the document.
   ///
-  /// See <https://generator3.swagger.io/index.html?url=https://autogram.slovensko.digital/openapi.yaml#/Mobile2App/get_documents__guid__validation>
-  Future<DocumentValidationResponseBody> getDocumentValidation(
+  /// See <https://generator3.swagger.io/index.html?url=https://autogram.slovensko.digital/openapi.yaml#/Mobile2App/get_documents__guid__validate>
+  Future<DocumentValidationResponseBody?> getDocumentValidation(
     String documentId,
   );
 
diff --git a/pubspec.yaml b/pubspec.yaml
index 749f9ff..676a332 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: autogram_sign
 description: "Autogram service REST API client"
-version: 0.4.2
+version: 0.4.3
 homepage: ""
 
 environment:
diff --git a/test/unwap_test.dart b/test/unwap_test.dart
index b8a4f94..9dfb196 100644
--- a/test/unwap_test.dart
+++ b/test/unwap_test.dart
@@ -15,6 +15,14 @@ void main() {
       expect(actual, "Test");
     });
 
+    test('unwrap returns nullable value for 200 status code', () {
+      final httpResponse = http.Response('"Test"', 200);
+      final response = chopper.Response<String?>(httpResponse, "Test");
+      final actual = unwrap(response);
+
+      expect(actual, "Test");
+    });
+
     test('unwrap returns nothing for 204 status code with no body', () {
       final httpResponse = http.Response('', 204);
       final response = chopper.Response<dynamic>(httpResponse, null);