diff --git a/src/Foundation/ErrorHandling/JsonApiFormatter.php b/src/Foundation/ErrorHandling/JsonApiFormatter.php
index bebdf9d153..4196012e24 100644
--- a/src/Foundation/ErrorHandling/JsonApiFormatter.php
+++ b/src/Foundation/ErrorHandling/JsonApiFormatter.php
@@ -26,12 +26,21 @@ class JsonApiFormatter implements HttpFormatter
     public function format(HandledError $error, Request $request): Response
     {
         $document = new Document;
-        $document->setErrors([
-            [
-                'status' => (string) $error->getStatusCode(),
-                'code' => $error->getType(),
-            ],
-        ]);
+
+        $data = [
+            'status' => (string) $error->getStatusCode(),
+            'code' => $error->getType(),
+        ];
+        $details = $error->getDetails();
+
+        if (empty($details)) {
+            $document->setErrors([$data]);
+        } else {
+            $document->setErrors(array_map(
+                function ($row) use ($data) { return array_merge($data, $row); },
+                $details
+            ));
+        }
 
         return new JsonApiResponse($document, $error->getStatusCode());
     }
diff --git a/tests/integration/api/users/CreationTest.php b/tests/integration/api/users/CreationTest.php
index 20963a0a82..4d2bd68a18 100644
--- a/tests/integration/api/users/CreationTest.php
+++ b/tests/integration/api/users/CreationTest.php
@@ -58,6 +58,32 @@ public function cannot_create_user_without_data()
         );
 
         $this->assertEquals(422, $response->getStatusCode());
+
+        // The response body should contain details about the failed validation
+        $body = (string) $response->getBody();
+        $this->assertJson($body);
+        $this->assertEquals([
+            'errors' => [
+                [
+                    'status' => '422',
+                    'code' => 'validation_error',
+                    'detail' => 'validation.required',
+                    'source' => ['pointer' => '/data/attributes/username'],
+                ],
+                [
+                    'status' => '422',
+                    'code' => 'validation_error',
+                    'detail' => 'validation.required',
+                    'source' => ['pointer' => '/data/attributes/email'],
+                ],
+                [
+                    'status' => '422',
+                    'code' => 'validation_error',
+                    'detail' => 'validation.required',
+                    'source' => ['pointer' => '/data/attributes/password'],
+                ],
+            ],
+        ], json_decode($body, true));
     }
 
     /**