diff --git a/collects/typed-scheme/private/base-env.rkt b/collects/typed-scheme/private/base-env.rkt
index cd4dbe71..072c20c0 100644
--- a/collects/typed-scheme/private/base-env.rkt
+++ b/collects/typed-scheme/private/base-env.rkt
@@ -1,16 +1,17 @@
 #lang s-exp "env-lang.rkt"
 
 (require
- scheme/tcp
- scheme
- scheme/unsafe/ops
- scheme/fixnum
+ racket/tcp
+ racket
+ racket/unsafe/ops
+ racket/fixnum
  (only-in rnrs/lists-6 fold-left)
  '#%paramz
  "extra-procs.rkt"
  (only-in '#%kernel [apply kernel:apply])
  (only-in racket/private/pre-base new-apply-proc)
- (for-syntax (only-in racket/private/pre-base new-apply-proc))
+ (for-syntax (only-in racket/private/pre-base new-apply-proc)
+             #;racket/string)
  scheme/promise scheme/system
  (only-in string-constants/private/only-once maybe-print-message)
  (only-in mzscheme make-namespace)
@@ -827,6 +828,12 @@
  (-poly (a) ((list (-vec a)) -Integer . ->* . (-values (list (-vec a) (-vec a)))))]
 
 
+;; racket/string
+[string-join (-> (-lst -String) -String -String)]
+[string-append*
+ (cl->* (-> (-lst -String) -String)
+        (-> -String (-lst -String) -String))]
+
 ;; scheme/system
 [system (-String . -> . -Boolean)]
 [system* ((list -Pathlike) -String . ->* . -Boolean)]
diff --git a/collects/typed-scheme/private/base-special-env.rkt b/collects/typed-scheme/private/base-special-env.rkt
index c4933663..0ccb7b2e 100644
--- a/collects/typed-scheme/private/base-special-env.rkt
+++ b/collects/typed-scheme/private/base-special-env.rkt
@@ -1,4 +1,4 @@
-#lang scheme/base
+#lang racket/base
 
 ;; these are libraries providing functions we add types to that are not in scheme/base
 (require
@@ -66,9 +66,14 @@
      [year-day : -Number]
      [dst? : -Boolean]
      [time-zone-offset : -Number]))
+  
+  (define-hierarchy arity-at-least
+    ([value : -Nat]))
 
   (define-hierarchy exn
     ([message : -String] [continuation-marks : -Cont-Mark-Set])
+    
+    (define-hierarchy exn:break ([continuation : top-func]))
 
     (define-hierarchy exn:fail ()