diff --git a/js/gdm/util.js b/js/gdm/util.js
index 092b40231..bba03c0be 100644
--- a/js/gdm/util.js
+++ b/js/gdm/util.js
@@ -103,6 +103,7 @@ export const MessageType = {
     HINT: 1,
     INFO: 2,
     ERROR: 3,
+    BACKGROUND: 4,
 };
 
 const FingerprintReaderType = {