diff --git a/apps/nextjs/package.json b/apps/nextjs/package.json
index addbb43..2f2d9e3 100644
--- a/apps/nextjs/package.json
+++ b/apps/nextjs/package.json
@@ -30,6 +30,6 @@
     "@types/react-dom": "latest",
     "cross-env": "latest",
     "eslint-config-next": "latest",
-    "typescript": "latest"
+    "typescript": "5.4.4"
   }
 }
diff --git a/apps/storybook/package.json b/apps/storybook/package.json
index 479974e..6a514ad 100644
--- a/apps/storybook/package.json
+++ b/apps/storybook/package.json
@@ -63,7 +63,7 @@
     "react-dom": "^18.2.0",
     "react-hook-form": "7.48.2",
     "storybook": "8.0.6",
-    "typescript": "latest",
+    "typescript": "5.4.4",
     "vite": "^5.2.8"
   }
 }
diff --git a/package.json b/package.json
index 64c239c..473656d 100644
--- a/package.json
+++ b/package.json
@@ -24,13 +24,13 @@
     "sb-start": "cd apps/storybook && yarn build-storybook && yarn start-storybook",
     "check-types": "cd packages/rhf-mui && tsc --noemit",
     "lint": "eslint apps/nextjs/src/** packages/rhf-mui/src/** apps/storybook/stories/** apps/storybook/src/**",
-    "lint:fix": "npm run lint -- --fix",
+    "lint:fix": "yarn run lint -- --fix",
     "prettier": "npx prettier apps/nextjs/src/** packages/rhf-mui/src/** apps/storybook/stories/** apps/storybook/src/** --check",
     "prettier:fix": "prettier --write \"**/*.{js,ts,tsx}\"",
     "deploy": "yarm build && cd apps/storybook/storybook-static && vercel --name react-hook-form-material-ui --prod",
     "build": "yarn lint:fix && yarn prettier:fix && cd packages/rhf-mui && yarn build",
     "upgrade:sb": "yarn up '@storybook/*' storybook -E",
-    "upgrade:typescript": "yarn up typescript@latest",
+    "upgrade:typescript": "yarn up typescript -E",
     "upgrade:rhf": "yarn up react-hook-form -E",
     "upgrade:mui": "yarn up '@mui/*' date-fns '@emotion/*' -E",
     "test": "cd apps/storybook && yarn chromatic"
@@ -44,7 +44,7 @@
     "release": "^6.3.1",
     "simple-git-hooks": "^2.8.1",
     "turbo": "^1.6.3",
-    "typescript": "latest"
+    "typescript": "5.4.4"
   },
   "packageManager": "yarn@1.22.19",
   "lint-staged": {
diff --git a/packages/rhf-mui/package.json b/packages/rhf-mui/package.json
index 53cb951..12fa8da 100644
--- a/packages/rhf-mui/package.json
+++ b/packages/rhf-mui/package.json
@@ -74,7 +74,7 @@
     "react-hook-form": "7.48.2",
     "release": "^6.3.1",
     "tsup": "^6.1.2",
-    "typescript": "latest"
+    "typescript": "5.4.4"
   },
   "simple-git-hooks": {
     "pre-commit": "npx lint-staged"
diff --git a/packages/rhf-mui/src/test/TestComponent.tsx b/packages/rhf-mui/src/test/TestComponent.tsx
deleted file mode 100644
index 5768e12..0000000
--- a/packages/rhf-mui/src/test/TestComponent.tsx
+++ /dev/null
@@ -1,15 +0,0 @@
-import {FormContainer} from '../FormContainer'
-import {TextFieldElement} from '../TextFieldElement'
-import {useForm} from 'react-hook-form'
-
-function TestComponent() {
-  const context = useForm()
-  return (
-    <FormContainer formContext={context}>
-      <TextFieldElement
-        control={context.control}
-        name={'textfield'}
-      ></TextFieldElement>
-    </FormContainer>
-  )
-}
diff --git a/packages/rhf-mui/src/utils.ts b/packages/rhf-mui/src/utils.ts
index 8ad1c85..8c34858 100644
--- a/packages/rhf-mui/src/utils.ts
+++ b/packages/rhf-mui/src/utils.ts
@@ -13,9 +13,9 @@ export function hasOwnProperty<X, Y extends PropertyKey>(
 
 export function getTimezone<TDate>(
   adapter: ReturnType<typeof useLocalizationContext>,
-  value: TDate | null
+  value: TDate
 ): string | null {
-  return value == null || !adapter.utils.isValid(value)
+  return value == null || !adapter.utils.isValid(value as unknown as Date)
     ? null
-    : adapter.utils.getTimezone(value)
+    : adapter.utils.getTimezone(value as unknown as Date)
 }