diff --git a/app/config/config-default.js b/app/config/config-default.js
index f19a76ad..d0190f6b 100644
--- a/app/config/config-default.js
+++ b/app/config/config-default.js
@@ -27,6 +27,7 @@ module.exports = {
     foregroundColor: '#fff',
 
     // terminal background color
+    // opacity is only supported on macOS
     backgroundColor: '#000',
 
     // border color (window, tabs)