diff --git a/collects/typed-scheme/env/lexical-env.rkt b/collects/typed-scheme/env/lexical-env.rkt
index 285faa2d..60063904 100644
--- a/collects/typed-scheme/env/lexical-env.rkt
+++ b/collects/typed-scheme/env/lexical-env.rkt
@@ -10,6 +10,7 @@
 	 "type-env-structs.rkt"
          "global-env.rkt"
 	 unstable/mutated-vars syntax/id-table
+         (for-syntax syntax/parse syntax/parse/experimental/contract racket/base)
          (only-in scheme/contract ->* -> or/c any/c listof cons/c)
          (utils tc-utils)
          (only-in (rep type-rep) Type/c)
@@ -17,10 +18,9 @@
 	 (except-in (types utils convenience) -> ->*))
 
 (provide lexical-env with-lexical-env with-lexical-env/extend
-         with-lexical-env/extend/props)
+         with-lexical-env/extend/props update-type/lexical)
 (provide/cond-contract
- [lookup-type/lexical ((identifier?) (prop-env? #:fail (or/c #f (-> any/c #f))) . ->* . (or/c Type/c #f))]
- [update-type/lexical (((identifier? Type/c . -> . Type/c) identifier?) (prop-env?) . ->* . env?)])
+ [lookup-type/lexical ((identifier?) (prop-env? #:fail (or/c #f (-> any/c #f))) . ->* . (or/c Type/c #f))])
 
 ;; the current lexical environment
 (define lexical-env (make-parameter (make-empty-prop-env (make-immutable-free-id-table))))
@@ -45,16 +45,20 @@
 ;; refine the type of i in the lexical env
 ;; (identifier type -> type) identifier -> environment
 ;; a macro for inlining :(
-(define-syntax-rule (update-type/lexical f i env)
-  ;; check if i is ever the target of a set!
-  (if (is-var-mutated? i)
-      ;; if it is, we do nothing
-      env
-      ;; otherwise, refine the type
-      (parameterize
-          ([current-orig-stx i])
-        (let* ([v (lookup-type/lexical i env #:fail (lambda _ Univ))]
-               [new-v (f i v)]
-               [new-env (extend env i new-v)])
-          new-env))))
-
+(define-syntax (update-type/lexical stx)
+  (syntax-parse stx
+    [(_ f i env)
+     #:declare f (expr/c #'(identifier? Type/c . -> . Type/c))
+     #:declare i (expr/c #'identifier?)
+     #:declare env (expr/c #'prop-env?)
+     ;; check if i is ever the target of a set!
+     #'(if (is-var-mutated? i)
+           ;; if it is, we do nothing
+           env
+           ;; otherwise, refine the type
+           (parameterize
+               ([current-orig-stx i])
+             (let* ([v (lookup-type/lexical i env #:fail (lambda _ Univ))]
+                    [new-v (f i v)]
+                    [new-env (extend env i new-v)])
+               new-env)))]))