diff --git a/lib/api.php b/lib/api.php
index 8d728d4311..0fce109a42 100644
--- a/lib/api.php
+++ b/lib/api.php
@@ -94,6 +94,8 @@ class OC_API {
 				$response = new OC_OCS_Result(null, 998, 'Api method not found');
 			}
 		} else {
+			header('WWW-Authenticate: Basic realm="Authorization Required"');
+			header('HTTP/1.0 401 Unauthorized');
 			$response = new OC_OCS_Result(null, 997, 'Unauthorised');
 		}
 		// Send the response