diff --git a/backend/src/app/rpc/commands/files_thumbnails.clj b/backend/src/app/rpc/commands/files_thumbnails.clj
index 9d64ec504d..c74f023b9d 100644
--- a/backend/src/app/rpc/commands/files_thumbnails.clj
+++ b/backend/src/app/rpc/commands/files_thumbnails.clj
@@ -185,7 +185,7 @@
   [:map {:title "PartialFile"}
    [:id ::sm/uuid]
    [:revn {:min 0} ::sm/int]
-   [:page :any]])
+   [:page [:map-of :keyword ::sm/any]]])
 
 (sv/defmethod ::get-file-data-for-thumbnail
   "Retrieves the data for generate the thumbnail of the file. Used
diff --git a/common/src/app/common/files/changes.cljc b/common/src/app/common/files/changes.cljc
index d9965ce556..8915402b06 100644
--- a/common/src/app/common/files/changes.cljc
+++ b/common/src/app/common/files/changes.cljc
@@ -418,7 +418,14 @@
       [:type [:= :set-token-set]]
       [:set-name :string]
       [:group? :boolean]
-      [:token-set [:maybe [:fn ctob/token-set?]]]]]
+
+      ;; FIXME: we should not pass private types as part of changes
+      ;; protocol, the changes protocol should reflect a
+      ;; method/protocol for perform surgical operations on file data,
+      ;; this has nothing todo with internal types of a file data
+      ;; structure.
+      [:token-set {:gen/gen (sg/generator ctob/schema:token-set)}
+       [:maybe [:fn ctob/token-set?]]]]]
 
     [:set-token
      [:map {:title "SetTokenChange"}
diff --git a/common/src/app/common/types/tokens_lib.cljc b/common/src/app/common/types/tokens_lib.cljc
index a802679a2c..498801f2d8 100644
--- a/common/src/app/common/types/tokens_lib.cljc
+++ b/common/src/app/common/types/tokens_lib.cljc
@@ -186,6 +186,10 @@
                           :modified-at modified-at
                           :tokens tokens})])
 
+  #?@(:clj
+      [json/JSONWriter
+       (-write [this writter options] (json/-write (deref this) writter options))])
+
   #?@(:cljs [cljs.core/IEncodeJS
              (-clj->js [_] (js-obj "id" (clj->js id)
                                    "name" (clj->js name)
@@ -292,7 +296,9 @@
 (declare make-token-set)
 
 (def schema:token-set
-  (sm/required-keys schema:token-set-attrs))
+  [:schema {:gen/gen (->> (sg/generator schema:token-set-attrs)
+                          (sg/fmap #(make-token-set %)))}
+   (sm/required-keys schema:token-set-attrs)])
 
 (sm/register! ::token-set schema:token-set) ;; need to register for the recursive schema of token-sets