diff --git a/src/modules/config.js b/src/modules/config.js
index 1c04845a85..522940f6b4 100644
--- a/src/modules/config.js
+++ b/src/modules/config.js
@@ -5,6 +5,7 @@ const browserLocale = (window.navigator.language || 'en').split('-')[0]
 
 const defaultState = {
   colors: {},
+  collapseMessageWithSubject: undefined,
   hideAttachments: false,
   hideAttachmentsInConv: false,
   hideNsfw: true,