diff --git a/main.rkt b/main.rkt
index 8edeb8f..c5b6be0 100644
--- a/main.rkt
+++ b/main.rkt
@@ -6,11 +6,10 @@
   [coverage/c contract?]
   [file-coverage/c contract?]
   [test-files! (->* () (#:submod symbol?)
-                    #:rest (listof path-string?)
-                    ;; TODO when we figure out the contract issue we will change this
-                    #;
+                    #:rest
                     (listof (or/c path-string?
-                                  (list/c path-string? (vectorof string?))))
+                                  (list/c path-string? (vectorof string?
+                                                                 #:immutable #t))))
                     any)]
   [clear-coverage! (-> any)]
   [get-test-coverage (-> coverage/c)]
diff --git a/raco.rkt b/raco.rkt
index eb57b04..43bd700 100644
--- a/raco.rkt
+++ b/raco.rkt
@@ -4,11 +4,10 @@
          racket/match
          racket/contract/base
          racket/function
-         "cover.rkt"
+         "main.rkt"
          (only-in "private/contracts.rkt" coverage-gen/c)
          "private/shared.rkt"
          "private/file-utils.rkt"
-         "private/format-utils.rkt"
          (only-in (submod compiler/commands/test paths) collection-paths)
          pkg/lib)
 
@@ -139,7 +138,7 @@
         null
         (map (lambda (x)
                (list (->absolute (car x))
-                     (list->vector (cadr x))))
+                     (vector->immutable-vector (list->vector (cadr x)))))
              new-argv)))
   (define full-argv (append expanded-argv args))
   (if (should-omit? (current-directory) full-omits)