diff --git a/src/asciinema/endpoint/asciicasts.clj b/src/asciinema/endpoint/asciicasts.clj
index 687e888..a4517ae 100644
--- a/src/asciinema/endpoint/asciicasts.clj
+++ b/src/asciinema/endpoint/asciicasts.clj
@@ -7,7 +7,7 @@
              [user-database :as udb]]
             [asciinema.model.asciicast :as asciicast]
             [asciinema.util.io :refer [with-tmp-dir]]
-            [asciinema.yada :refer [resource]]
+            [asciinema.yada :refer [resource not-found-model]]
             [clj-time.core :as t]
             [clojure.java
              [io :as io]
@@ -103,4 +103,4 @@
 (defn asciicasts-endpoint [{:keys [db file-store exp-set executor]}]
   ["" [["/a/" [[[:token ".json"] (asciicast-json-resource db file-store)]
                [[:token ".png"] (asciicast-png-resource db file-store exp-set executor)]]]
-       [true (yada/as-resource nil)]]])
+       [true (yada/resource not-found-model)]]])
diff --git a/src/asciinema/yada.clj b/src/asciinema/yada.clj
index e15788e..e2dafcc 100644
--- a/src/asciinema/yada.clj
+++ b/src/asciinema/yada.clj
@@ -2,14 +2,18 @@
   (:require [clojure.java.io :as io]
             [yada.yada :as yada]))
 
-(defn not-found-response [ctx]
-  (case (yada/content-type ctx)
-    "text/html" (io/input-stream (io/resource "asciinema/errors/404.html"))
-    "Not found"))
+(def not-found-model
+  {:produces
+   #{"text/html" "text/plain"}
+   :response
+   (fn [ctx]
+     (assoc (:response ctx)
+            :status 404
+            :body (case (yada/content-type ctx)
+                    "text/html" (io/input-stream (io/resource "asciinema/errors/404.html"))
+                    "Not found")))})
 
 (defn resource [model]
   (-> model
-      (update-in [:responses 404] #(or %
-                                       {:produces #{"text/html" "text/plain"}
-                                        :response not-found-response}))
+      (update-in [:responses 404] #(or % not-found-model))
       yada/resource))