diff --git a/src/CacheSim/Model.elm b/src/CacheSim/Model.elm
index f068892..f188915 100644
--- a/src/CacheSim/Model.elm
+++ b/src/CacheSim/Model.elm
@@ -1,11 +1,14 @@
 module CacheSim.Model exposing (..)
 import CacheSim.Raw exposing (..)
+import CacheSim.Hierarchy exposing (..)
 
 type alias Model =
     { rawHierarchy : RawCacheModelHierarchy
+    , hierarchy : Maybe CacheHierarchy
     }
 type alias Flags = ()
 type Msg
     = ChangeRawModel Int (RawCacheModel -> RawCacheModel)
     | CreateRawModel
     | DeleteRawModel Int
+    | UseHierarchy (Maybe CacheModelHierarchy)
diff --git a/src/CacheSim/Update.elm b/src/CacheSim/Update.elm
index 5b48e2c..c69d6c0 100644
--- a/src/CacheSim/Update.elm
+++ b/src/CacheSim/Update.elm
@@ -1,5 +1,6 @@
 module CacheSim.Update exposing (..)
 import CacheSim.Model exposing (..)
+import CacheSim.Hierarchy exposing (..)
 import CacheSim.Raw exposing (..)
 import CacheSim.IntMap exposing (..)
 
@@ -27,3 +28,11 @@ updateDeleteRawModel l m =
         cmd = Cmd.none
     in
         (newModel, cmd)
+
+updateUseHierarchy : Maybe CacheModelHierarchy -> Model -> (Model, Cmd Msg)
+updateUseHierarchy cmh m =
+    let
+        newModel = { m | hierarchy = Maybe.map freshCacheHierarchy cmh }
+        cmd = Cmd.none
+    in
+        (newModel, cmd)
diff --git a/src/CacheSim/View.elm b/src/CacheSim/View.elm
index f574b3a..bed1316 100644
--- a/src/CacheSim/View.elm
+++ b/src/CacheSim/View.elm
@@ -64,7 +64,9 @@ viewRawCacheModelHierarchy rcmh =
                 Err e -> viewError False e
         
         newButton = button "Add level" CreateRawModel
-        useButton = optionalButton isValid "Use hierarchy" CreateRawModel
+        useButton = case translationResult of
+            Ok cmh -> optionalButton True "Use hierarchy" (UseHierarchy <| Just cmh)
+            Err _ -> optionalButton False "Use hierarchy" (UseHierarchy Nothing)
     in
         div [ class "cache-model-hierarchy" ]
             [ h2 [] [ text "Cache hierarchy" ]
diff --git a/src/Main.elm b/src/Main.elm
index 3a5ce63..447ba9f 100644
--- a/src/Main.elm
+++ b/src/Main.elm
@@ -17,6 +17,7 @@ init f =
     let
         initialModel =
             { rawHierarchy = testCacheModelHierarchy
+            , hierarchy = Nothing
             }
     in
         (initialModel, Cmd.none)
@@ -33,6 +34,7 @@ update msg m =
         ChangeRawModel l f -> updateChangeRawModel l f m
         CreateRawModel -> updateCreateRawModel m
         DeleteRawModel i -> updateDeleteRawModel i m
+        UseHierarchy cmh -> updateUseHierarchy cmh m
 
 subscriptions : Model -> Sub Msg
 subscriptions m = Sub.none