diff --git a/cylc/flow/etc/syntax/cylc.lang b/cylc/flow/etc/syntax/cylc.lang
index 0270c7f3cfc..0df851c4bcb 100644
--- a/cylc/flow/etc/syntax/cylc.lang
+++ b/cylc/flow/etc/syntax/cylc.lang
@@ -10,7 +10,7 @@
  /usr/share/gtksourceview-2.0/language-specs/
 
  If your installation uses GNOME 3, the '2.0' in the paths will need
- to be '3.0'.
+ to be '3.0'. If your installation uses GNOME 4, '2.0' will become '4'.
 
  If using gedit, gedit will need to be totally closed down and reloaded.