diff --git a/collects/racket/match/gen-match.rkt b/collects/racket/match/gen-match.rkt
index 292c71edc9..18c2d770cc 100644
--- a/collects/racket/match/gen-match.rkt
+++ b/collects/racket/match/gen-match.rkt
@@ -10,6 +10,7 @@
 ;; go : syntax syntax syntax -> syntax
 (define (go/one parse stx expr clauses)
   (define-syntax-class cl
+    #:description "a clause with a pattern and a result"
     (pattern [p . rhs]
              #:with res (syntax/loc this-syntax [(p) . rhs])))
   (syntax-parse clauses