diff --git a/collects/web-server/scribblings/servlet.scrbl b/collects/web-server/scribblings/servlet.scrbl
index 9d227da96b..9fbb335f58 100644
--- a/collects/web-server/scribblings/servlet.scrbl
+++ b/collects/web-server/scribblings/servlet.scrbl
@@ -103,7 +103,8 @@ related to HTTP request data structures.
  and the content @scheme[content].
 }
 
-@defproc[(bindings-assq [binds (listof binding?)])
+@defproc[(bindings-assq [id bytes?]
+                        [binds (listof binding?)])
          (or/c false/c binding?)]{
  Returns the binding with an id equal to @scheme[id] from @scheme[binds] or @scheme[#f].
 }