diff --git a/src/hottub/screen.clj b/src/hottub/screen.clj
index 47702e9..1793f9e 100644
--- a/src/hottub/screen.clj
+++ b/src/hottub/screen.clj
@@ -3,6 +3,9 @@
 (defmulti screen-from-spec (fn [spec] (:id spec)))
 (defmulti spec-from-screen (fn [screen] (:id screen)))
 
+(defmethod spec-from-screen :default [screen] {})
+(defmethod screen-from-spec :default [spec] spec)
+
 (defn- -screen-from-spec [spec] (assoc (screen-from-spec spec) :id (:id spec)))
 (defn- -spec-from-screen [screen] (assoc (spec-from-screen screen) :id (:id screen)))