diff --git a/README b/README
index fd0c9e9d84dc66dcad16f5be50da257d4333a1cd..87a5bf4dfca2f8806f6a24b14df31a2134b8e422 100644
--- a/README
+++ b/README
@@ -25,6 +25,8 @@ the following line:
 
 export QT_QPA_PLATFORMTHEME=qt6ct
 
+(or qt5ct for compatibility)
+
 Now restart X11 server to take the changes effect.
 
 Extra build options (for advanced users only):