diff --git a/package.json b/package.json
index 7d35dc0..ffb3339 100644
--- a/package.json
+++ b/package.json
@@ -38,7 +38,7 @@
     "---------- Linting ----------------------------------------------------": "",
     "ts": "tsc --noEmit",
     "---------- helper commands --------------------------------------------": "",
-    "prettier": "npx prettier --write \"./**/*.{ts,tsx,js,jsx,json,md}\"",
+    "prettier": "prettier --write \"./**/*.{ts,tsx,js,jsx,json,md}\"",
     "up": "yarn upgrade-interactive --latest",
     "-----------------------------------------------------------------------": ""
   },
@@ -64,6 +64,7 @@
     "jest-mock-console": "^2.0.0",
     "milliseconds": "^1.0.3",
     "mobx": "^6.3.0",
+    "prettier": "^2.8.4",
     "ts-jest": "^28.0.4",
     "typescript": "^4.2.4"
   },
diff --git a/src/PersistStore.ts b/src/PersistStore.ts
index 49cd6e4..d31946d 100644
--- a/src/PersistStore.ts
+++ b/src/PersistStore.ts
@@ -153,17 +153,10 @@ export class PersistStore<T, P extends keyof T> {
           actionPersistWarningIf(isActionProperty, String(property.key));
 
           if (!isComputedProperty && !isActionProperty) {
-            let propertyData = property.serialize(target[property.key]);
-
-            if (propertyData instanceof ObservableMap) {
-              const mapArray: any = [];
-              propertyData.forEach((v, k) => {
-                mapArray.push([k, toJS(v)]);
-              });
-              propertyData = mapArray;
-            }
+            const propertyData = property.serialize(target[property.key]);
 
-            propertiesToWatch[property.key] = toJS(propertyData);
+            propertiesToWatch[property.key] =
+              typeof propertyData === 'undefined' ? undefined : JSON.parse(JSON.stringify(propertyData));
           }
         });
 
diff --git a/yarn.lock b/yarn.lock
index c87051e..2fdced9 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3261,6 +3261,11 @@ prelude-ls@~1.1.2:
   resolved "https://registry.yarnpkg.com/prelude-ls/-/prelude-ls-1.1.2.tgz#21932a549f5e52ffd9a827f570e04be62a97da54"
   integrity sha512-ESF23V4SKG6lVSGZgYNpbsiaAkdab6ZgOxe52p7+Kid3W3u3bxR4Vfd/o21dmN7jSt0IwgZ4v5MUd26FEtXE9w==
 
+prettier@^2.8.4:
+  version "2.8.4"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-2.8.4.tgz#34dd2595629bfbb79d344ac4a91ff948694463c3"
+  integrity sha512-vIS4Rlc2FNh0BySk3Wkd6xmwxB0FpOndW5fisM5H8hsZSxU2VWVB5CWIkIjWvrHjIhxk2g3bfMKM87zNTrZddw==
+
 pretty-format@^27.0.0, pretty-format@^27.5.1:
   version "27.5.1"
   resolved "https://registry.yarnpkg.com/pretty-format/-/pretty-format-27.5.1.tgz#2181879fdea51a7a5851fb39d920faa63f01d88e"