diff --git a/CHANGELOG.md b/CHANGELOG.md
index e9a2b554..5ca7fec1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,7 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## Fixed
 
 - #480: Make the app GDPR - new EU privacy regulations compliant.
-
+- #489: REST API response headers must use the Content-Type application/json value.
 
 ## [1.3.1]
 
diff --git a/src/engine/Api/V1/Response.php b/src/engine/Api/V1/Response.php
index 490ec050..6945167b 100644
--- a/src/engine/Api/V1/Response.php
+++ b/src/engine/Api/V1/Response.php
@@ -143,6 +143,7 @@ class Response {
         $header = $status ? $status->get() : '200 OK';
 
         header('HTTP/1.0 ' . $header);
+        header('Content-Type: application/json');
 
         echo json_encode($this->response, JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT);