diff --git a/collects/syntax/parse/private/kws.rkt b/collects/syntax/parse/private/kws.rkt
index c9f94b3c07..00e1ebb4fd 100644
--- a/collects/syntax/parse/private/kws.rkt
+++ b/collects/syntax/parse/private/kws.rkt
@@ -46,7 +46,7 @@ An Arity is
                             (arity-maxpos arity)
                             (arity-minkws arity)
                             (arity-maxkws arity)
-                            pos-count keywords)])
+                            pos-count (sort keywords keyword<?))])
     (when msg
       (proc msg))))
 
@@ -55,7 +55,7 @@ An Arity is
                                 (arity-maxpos arity)
                                 (arity-minkws arity)
                                 (arity-maxkws arity)
-                                pos-count keywords)])
+                                pos-count (sort keywords keyword<?))])
     (when msg
       (proc msg))))
 
diff --git a/collects/tests/stxparse/stxclass.rkt b/collects/tests/stxparse/stxclass.rkt
index b64a984b9c..cd7bd546df 100644
--- a/collects/tests/stxparse/stxclass.rkt
+++ b/collects/tests/stxparse/stxclass.rkt
@@ -194,3 +194,9 @@
    #:with c #'c0
    #:declare c (Nat> (syntax-e #'b0))
    (void)])
+
+(define-syntax-class (Nat-Between #:lo lo #:hi hi)
+  #:description (format "~s <= Nat <= ~s" lo hi)
+  (pattern x:nat #:when (<= lo (syntax-e #'x) hi)))
+(syntax-parse #'5
+  [(~var _ (Nat-Between #:lo 0 #:hi 10)) (void)])