diff --git a/collects/typed-scheme/private/subtype.ss b/collects/typed-scheme/private/subtype.ss
index 5f7e3595..04f3c89b 100644
--- a/collects/typed-scheme/private/subtype.ss
+++ b/collects/typed-scheme/private/subtype.ss
@@ -1,6 +1,6 @@
 #lang scheme/base
 
-(require "type-rep.ss" "unify.ss" "type-utils.ss"
+(require (except-in "type-rep.ss" sub-eff) "unify.ss" "type-utils.ss"
          "tc-utils.ss"
          "effect-rep.ss"
          "type-comparison.ss"
diff --git a/collects/typed-scheme/private/type-effect-convenience.ss b/collects/typed-scheme/private/type-effect-convenience.ss
index 22317db1..73c11ef9 100644
--- a/collects/typed-scheme/private/type-effect-convenience.ss
+++ b/collects/typed-scheme/private/type-effect-convenience.ss
@@ -69,7 +69,11 @@
 (define make-arr*
   (case-lambda [(dom rng) (make-arr* dom rng #f (list) (list))]
                [(dom rng rest) (make-arr dom rng rest #f (list) (list))]
-               [(dom rng rest eff1 eff2) (make-arr dom rng rest #f eff1 eff2)]))
+               [(dom rng rest eff1 eff2) (make-arr dom rng rest #f eff1 eff2)]
+               [(dom rng rest drest eff1 eff2) (make-arr dom rng rest drest eff1 eff2)]))
+
+(define (make-arr-dots dom rng dty dbound)
+  (make-arr* dom rng #f (cons dty dbound) null null))
 
 (define (make-promise-ty t)
   (make-Struct (string->uninterned-symbol "Promise") #f (list t) #f #f #'promise? values))
diff --git a/collects/typed-scheme/private/type-utils.ss b/collects/typed-scheme/private/type-utils.ss
index b82bf64a..a67bc677 100644
--- a/collects/typed-scheme/private/type-utils.ss
+++ b/collects/typed-scheme/private/type-utils.ss
@@ -10,6 +10,7 @@
 
 (provide fv fv/list
          substitute
+         substitute-dots
          subst-all
          subst 
          ret
@@ -26,7 +27,45 @@
   (define (sb t) (substitute image name t))
   (if (hash-ref (free-vars* target) name #f)
       (type-case sb target
-                 [#:F name* (if (eq? name* name) image target)])
+                 [#:F name* (if (eq? name* name) image target)]
+                 [#:arr dom rng rest drest thn-eff els-eff
+                        (begin
+                          (when (and (pair? drest)
+                                     (eq? name (cdr drest)))
+                            (int-err "substitute used on ... variable ~a" name))
+                          (make-arr (map sb dom)
+                                    (sb rng)
+                                    (and rest (sb rest))
+                                    (and drest (cons (sb (car drest)) (cdr drest)))
+                                    (map (lambda (e) (sub-eff sb e)) thn-eff)
+                                    (map (lambda (e) (sub-eff sb e)) els-eff)))])
+      target))
+
+;; substitute-dots : Listof[Type] Name Type -> Type
+(define (substitute-dots images name target)    
+  (define (sb t) (substitute-dots images name t))
+  (if (hash-ref (free-vars* target) name #f)
+      (type-case sb target
+                 [#:F name* (if (eq? name* name)
+                                (int-err "substitute-dots: got single variable ~a" name*)
+                                target)]
+                 [#:arr dom rng rest drest thn-eff els-eff
+                        (if (and (pair? drest)
+                                 (eq? name (cdr drest)))                            
+                            (make-arr (append 
+                                       (map sb dom)
+                                       (map (lambda (img) (substitute img name (car drest))) images))
+                                      (sb rng)
+                                      #f
+                                      #f
+                                      (map (lambda (e) (sub-eff sb e)) thn-eff)
+                                      (map (lambda (e) (sub-eff sb e)) els-eff))
+                            (make-arr (map sb dom)
+                                      (sb rng)
+                                      (and rest (sb rest))
+                                      (and drest (cons (sb (car drest)) (cdr drest)))
+                                      (map (lambda (e) (sub-eff sb e)) thn-eff)
+                                      (map (lambda (e) (sub-eff sb e)) els-eff)))])
       target))
 
 ;; substitute many variables