diff --git a/collects/tests/typed-scheme/fail/ht-infer.ss b/collects/tests/typed-scheme/fail/ht-infer.ss
new file mode 100644
index 00000000..19c97d8d
--- /dev/null
+++ b/collects/tests/typed-scheme/fail/ht-infer.ss
@@ -0,0 +1,29 @@
+#lang scheme/load
+
+(module before typed/scheme
+  
+  (provide (all-defined-out))
+  
+  (define-struct: Sigil ())
+  
+  (: list->english ((Listof String) -> String))
+  (define (list->english strs) (error 'fail))
+  
+  (define-type-alias (Set X) (HashTable X '()))
+  
+  (: empty-set (All (T) (-> (Set T))))
+  (define (empty-set) (error 'fail))
+  
+  (: set->list (All (T) ((Set T) -> (Listof T))))
+  (define (set->list set) (error 'fail))
+  )
+
+(module after typed/scheme
+  (require 'before)
+  
+  (: f ((Set Sigil) -> Any))
+  (define (f x1)
+    (let* ([x2 (set->list x1)])
+      (list->english x2)
+      (error 'NO! "Way!"))))
+
diff --git a/collects/typed-scheme/infer/infer-unit.ss b/collects/typed-scheme/infer/infer-unit.ss
index fdc6da25..b1609af1 100644
--- a/collects/typed-scheme/infer/infer-unit.ss
+++ b/collects/typed-scheme/infer/infer-unit.ss
@@ -387,7 +387,7 @@
           [((Box: e) (Box: e*))
            (cset-meet (cg e e*) (cg e* e))]
           [((Hashtable: s1 s2) (Hashtable: t1 t2))
-           ;; the key is contravariant, the value is invariant
+           ;; for mutable hash tables, both are invariant
            (cset-meet* (list (cg t1 s1) (cg s1 t1) (cg t2 s2) (cg s2 t2)))]
           [((Syntax: s1) (Syntax: s2))
            (cg s1 s2)]