diff --git a/utils.rkt b/utils.rkt
index 7dc9ca9..59f717d 100644
--- a/utils.rkt
+++ b/utils.rkt
@@ -135,11 +135,10 @@
 ;;; Produces a list of symbols appearing in the quoted expression
 ;;; passed in the first argument.
 (define (extract-symbols form)
-  (cond
-    [(symbol? form)
-     (list form)]
-    [(list? form)
-     (flatten (for/list ([x form]) (extract-symbols x)))]
+  (match form
+    [(? symbol?) (list form)]
+    [(? list?) (flatten (for/list ([x form])
+                          (extract-symbols x)))]
     [else '()]))