diff --git a/rs.rkt b/rs.rkt
index aa62ed5..9d85ed1 100644
--- a/rs.rkt
+++ b/rs.rkt
@@ -4,7 +4,7 @@
   (require typed/graph "utils.rkt" "dynamics.rkt")
 
   (provide
-   Species (struct-out reaction) Reaction ReactionSystem
+   Species (struct-out reaction) Reaction ReactionName ReactionSystem
    make-reaction enabled? list-enabled)
 
   (module+ test
@@ -18,6 +18,8 @@
     #:transparent
     #:type-name Reaction)
 
+  (define-type ReactionName Symbol)
+
   (: make-reaction (-> (Listof Species) (Listof Species) (Listof Species) Reaction))
   (define (make-reaction r i p) (reaction (list->set r)
                                           (list->set i)
@@ -41,9 +43,9 @@
       (check-false (enabled? (make-reaction '(a b) '(c d) '())
                              (set 'b 'e)))))
 
-  (define-type ReactionSystem (HashTable Symbol Reaction))
+  (define-type ReactionSystem (HashTable ReactionName Reaction))
 
-  (: list-enabled (-> ReactionSystem (Setof Species) (Listof Symbol)))
+  (: list-enabled (-> ReactionSystem (Setof Species) (Listof ReactionName)))
   (define (list-enabled rs s)
     (for/list ([(name reaction) (in-hash rs)]
                #:when (enabled? reaction s))
diff --git a/scribblings/rs.scrbl b/scribblings/rs.scrbl
index 05007e4..ad60f8a 100644
--- a/scribblings/rs.scrbl
+++ b/scribblings/rs.scrbl
@@ -47,6 +47,12 @@ The type of the instances of @racket[reaction].
 
 }
 
+@deftype[ReactionName]{
+
+A reaction name is any @racket[Symbol].
+
+}
+
 @defproc[(make-reaction [r (Listof Reaction)]
 			[i (Listof Reaction)]
 			[p (Listof Reaction)])
@@ -75,12 +81,13 @@ reactants are in the set and none of its inhibitors are.
 
 @deftype[ReactionSystem]{
 
-A reaction system is a dictionary mapping reaction names
-(@racket[Symbol]s) to @racket[Reaction]s.
+A reaction system is a dictionary mapping @racket[ReactionName]s to
+@racket[Reaction]s.
 
 }
 
-@defproc[(list-enabled [rs ReactionSystem] [s (Setof Species)]) (Listof Symbol)]{
+@defproc[(list-enabled [rs ReactionSystem] [s (Setof Species)])
+		       (Listof ReactionName)]{
 
 Returns the list of the names of reactions of @racket[rs] enabled on
 @racket[s].