diff --git a/thun/thun.pl b/thun/thun.pl
index 4a92b3b..f38243a 100644
--- a/thun/thun.pl
+++ b/thun/thun.pl
@@ -32,7 +32,7 @@ joy(InputString, StackIn, StackOut) :-
 /*
 Parser
 
-    joy :== number | '[' joy* ']' | chars
+    joy :== number | '[' joy* ']' | atom
 
 */