diff --git a/cover.rkt b/cover.rkt
index 0a8cb82..0134bea 100644
--- a/cover.rkt
+++ b/cover.rkt
@@ -19,7 +19,7 @@
 ;; PathString * -> Boolean
 ;; Test files and build coverage map
 ;; returns true if all tests passed
-(define (test-files! . paths)
+(define (test-files!  #:submod [submod-name 'test] . paths)
   (for ([path paths])
     (define p
       (if (absolute-path? path)
@@ -52,7 +52,7 @@
                            (apply old-check x))])
           (eval `(dynamic-require '(file ,p) #f))
           (namespace-require `(file ,p))
-          (define submod `(submod (file ,p) test))
+          (define submod `(submod (file ,p) ,submod-name))
           (when (module-declared? submod)
             (namespace-require submod)))))
     (not tests-failed)))
diff --git a/main.rkt b/main.rkt
index 8a76710..0330ad6 100644
--- a/main.rkt
+++ b/main.rkt
@@ -5,7 +5,7 @@
  (contract-out
   [coverage/c contract?]
   [file-coverage/c contract?]
-  [test-files! (->* () () #:rest (listof path-string?) any/c)]
+  [test-files! (->* () (#:submod symbol?) #:rest (listof path-string?) any/c)]
   [clear-coverage! (-> any)]
   [get-test-coverage (-> coverage/c)]
   [make-covered?
diff --git a/raco.rkt b/raco.rkt
index 6b55ade..83be241 100644
--- a/raco.rkt
+++ b/raco.rkt
@@ -12,6 +12,7 @@
   (define output-format "html")
   (define exclude-paths '())
   (define include-exts '())
+  (define submod 'test)
 
   (define args
      (command-line
@@ -36,6 +37,9 @@
       [("-i" "--include-extentions") f
        "include these extentions in files to cover."
        (set! include-exts (cons f include-exts))]
+      [("-s" "--submodule") s
+       "Run the given submodule instead of the test submodule"
+       (set! submod (string->symbol s))]
       #:args (file . files)
       (cons file files)))
   (define files (expand-directories args include-exts))
@@ -46,7 +50,7 @@
       [("raw") generate-raw-coverage]
       [else (error 'cover "given unknown coverage output format: ~s" output-format)]))
   (printf "generating test coverage for ~s\n" files)
-  (define passed (apply test-files! files))
+  (define passed (keyword-apply test-files! '(#:submod) (list submod) files))
   (define coverage (remove-excluded-paths (get-test-coverage) exclude-paths))
   (printf "dumping coverage info into ~s\n" coverage-dir)
   (generate-coverage coverage coverage-dir)
diff --git a/scribblings/api.scrbl b/scribblings/api.scrbl
index c5ab750..bcfbf75 100644
--- a/scribblings/api.scrbl
+++ b/scribblings/api.scrbl
@@ -9,11 +9,12 @@ In addition to a raco tool Cover provides racket bindings for running
 tests and collecting coverage information. The following are the basic
 functions of test coverage.
 
-@defproc[(test-files! (files path-string?) ...) any/c]{
+@defproc[(test-files! (#:submod submod symbol? 'test) (files path-string?) ...) any/c]{
 
-Tests all given @racket[files] and stores the coverage information. Returns
-false if tests failed. Test coverage information is still collected when test
-fail. Test coverage info is added to existing coverage info.}
+Runs all given @racket[files] and there submodule @racket[submod] (if it exitsts),
+storing the coverage information. Returns false if tests failed. Test coverage
+information is still collected when test fail. Test coverage info is added to
+existing coverage info.}
 
 @defproc[(clear-coverage!) any]{Clears all coverage information.}
 
diff --git a/scribblings/basics.scrbl b/scribblings/basics.scrbl
index 03254a7..1e2856d 100644
--- a/scribblings/basics.scrbl
+++ b/scribblings/basics.scrbl
@@ -37,4 +37,6 @@ The @exec{raco cover} command accepts the following flags:
                    used when expanding directories, searching for files to cover.}
          @item{@Flag{v} or @DFlag{verbose}
                --- enable verbose logging}
+         @item{@Flag{s} or @DFlag{submod}
+               --- run the given submodule instead of the test submodule.}
          ]