diff --git a/README.md b/README.md
index 4287d8d..b1a7ed4 100644
--- a/README.md
+++ b/README.md
@@ -105,7 +105,7 @@ For instance this program would use the external connector stubs to build up int
                  (retry-http* f backoff-fn (+ backoff-count 1)))))))
 
   (defn job [hostname :- str,
-             stages :- (list str),
+             stages :- (list? str?),
              job-timeout :- duration? :default (duration 3 :hours)]
              :- (union timeout? json?)
     """Run a wilson job, wait for the callback and process the result.