diff --git a/racket/src/schemify/known.rkt b/racket/src/schemify/known.rkt
index 1862765b7e..f104283722 100644
--- a/racket/src/schemify/known.rkt
+++ b/racket/src/schemify/known.rkt
@@ -56,7 +56,7 @@
 ;; literal for constant propagation:
 (struct known-literal (value) #:prefab #:omit-define-syntaxes #:super struct:known-consistent)
 
-;; procedure with arity mark; the procedure has to be a procedure from the host
+;; procedure with arity mask; the procedure has to be a procedure from the host
 ;; Scheme's perspective --- not an applicable struct or chaperoned procedure, which
 ;; means that parameters don't count
 (struct known-procedure (arity-mask) #:prefab #:omit-define-syntaxes #:super struct:known-consistent)