diff --git a/package.json b/package.json
index 76fb834807..958718be9e 100644
--- a/package.json
+++ b/package.json
@@ -218,7 +218,7 @@
     "ts-expect": "^1.3.0",
     "ts-node": "^10.2.1",
     "tslib": "^2.3.1",
-    "typescript": "4.3.5",
+    "typescript": "^4.4.3",
     "valtio": "^1.1.3",
     "wonka": "^4.0.15",
     "xstate": "^4.17.1",
diff --git a/src/core/store.ts b/src/core/store.ts
index 01f8b4046c..937827cceb 100644
--- a/src/core/store.ts
+++ b/src/core/store.ts
@@ -310,7 +310,7 @@ export const createStore = (
       } else if (errorOrPromise instanceof Error) {
         error = errorOrPromise
       } else {
-        error = new Error(errorOrPromise)
+        error = new Error(errorOrPromise as string)
       }
     }
     if (error) {
diff --git a/src/utils/splitAtom.ts b/src/utils/splitAtom.ts
index d05b6e03e8..062e3b90a7 100644
--- a/src/utils/splitAtom.ts
+++ b/src/utils/splitAtom.ts
@@ -69,7 +69,7 @@ export function splitAtom<Item, Key>(
             atom
           )
         }
-        return get(arrAtom)[index]
+        return get(arrAtom)[index] as Item
       }
       const write = (
         get: Getter,
@@ -81,7 +81,9 @@ export function splitAtom<Item, Key>(
           throw new Error('splitAtom: array index not found')
         }
         const prev = get(arrAtom)
-        const nextItem = isFunction(update) ? update(prev[index]) : update
+        const nextItem = isFunction(update)
+          ? update(prev[index] as Item)
+          : update
         set(arrAtom as WritableAtom<Item[], Item[]>, [
           ...prev.slice(0, index),
           nextItem,
diff --git a/src/utils/waitForAll.ts b/src/utils/waitForAll.ts
index de884b9669..ad0bbb26b8 100644
--- a/src/utils/waitForAll.ts
+++ b/src/utils/waitForAll.ts
@@ -51,9 +51,7 @@ const unwrapAtoms = <
 >(atoms: { [K in keyof Values]: Atom<Values[K]> }): Atom<unknown>[] =>
   Array.isArray(atoms)
     ? atoms
-    : Object.getOwnPropertyNames(atoms).map(
-        (key) => (atoms as Record<string, Atom<unknown>>)[key]
-      )
+    : Object.getOwnPropertyNames(atoms).map((key) => atoms[key as keyof Values])
 
 const wrapResults = <Values extends Record<string, unknown> | unknown[]>(
   atoms: { [K in keyof Values]: Atom<Values[K]> },
diff --git a/src/utils/weakCache.ts b/src/utils/weakCache.ts
index 2404d5d9de..a6fd2c7a8f 100644
--- a/src/utils/weakCache.ts
+++ b/src/utils/weakCache.ts
@@ -6,7 +6,7 @@ export const getWeakCacheItem = <T>(
 ): T | undefined => {
   while (true) {
     const [dep, ...rest] = deps
-    const entry = cache.get(dep)
+    const entry = cache.get(dep as object)
     if (!entry) {
       return
     }
@@ -25,10 +25,10 @@ export const setWeakCacheItem = <T>(
 ): void => {
   while (true) {
     const [dep, ...rest] = deps
-    let entry = cache.get(dep)
+    let entry = cache.get(dep as object)
     if (!entry) {
       entry = [new WeakMap()]
-      cache.set(dep, entry)
+      cache.set(dep as object, entry)
     }
     if (!rest.length) {
       entry[1] = item
diff --git a/tests/utils/atomFamily.test.tsx b/tests/utils/atomFamily.test.tsx
index 994091f4f7..3d5ea6f789 100644
--- a/tests/utils/atomFamily.test.tsx
+++ b/tests/utils/atomFamily.test.tsx
@@ -41,7 +41,7 @@ it('primitive atomFamily returns same reference for same parameters', async () =
 it('read-only derived atomFamily returns same reference for same parameters', async () => {
   const arrayAtom = atom([0])
   const myFamily = atomFamily<number, number>((num) =>
-    atom((get) => get(arrayAtom)[num])
+    atom((get) => get(arrayAtom)[num] as number)
   )
   expect(myFamily(0)).toEqual(myFamily(0))
   expect(myFamily(0)).not.toEqual(myFamily(1))
@@ -51,7 +51,7 @@ it('read-only derived atomFamily returns same reference for same parameters', as
 it('removed atom creates a new reference', async () => {
   const bigAtom = atom([0])
   const myFamily = atomFamily<number, number>((num) =>
-    atom((get) => get(bigAtom)[num])
+    atom((get) => get(bigAtom)[num] as number)
   )
 
   const savedReference = myFamily(0)
@@ -116,13 +116,15 @@ it('derived atomFamily functionality as usual', async () => {
 
   const myFamily = atomFamily<number, number, SetStateAction<number>>((param) =>
     atom(
-      (get) => get(arrayAtom)[param],
+      (get) => get(arrayAtom)[param] as number,
       (_, set, update) => {
         set(arrayAtom, (oldArray) => {
           if (typeof oldArray[param] === 'undefined') return oldArray
 
           const newValue =
-            typeof update === 'function' ? update(oldArray[param]) : update
+            typeof update === 'function'
+              ? update(oldArray[param] as number)
+              : update
 
           const newArray = [
             ...oldArray.slice(0, param),
@@ -206,11 +208,11 @@ it('custom equality function work', async () => {
   const bigAtom = atom([0])
 
   const badFamily = atomFamily<{ index: number }, number>((num) =>
-    atom((get) => get(bigAtom)[num.index])
+    atom((get) => get(bigAtom)[num.index] as number)
   )
 
   const goodFamily = atomFamily<{ index: number }, number>(
-    (num) => atom((get) => get(bigAtom)[num.index]),
+    (num) => atom((get) => get(bigAtom)[num.index] as number),
     (l, r) => l.index === r.index
   )
 
diff --git a/tests/utils/atomWithStorage.test.tsx b/tests/utils/atomWithStorage.test.tsx
index 39e142d718..8ebb6c413e 100644
--- a/tests/utils/atomWithStorage.test.tsx
+++ b/tests/utils/atomWithStorage.test.tsx
@@ -23,7 +23,7 @@ describe('atomWithStorage (sync)', () => {
       if (!(key in storageData)) {
         throw new Error('no value stored')
       }
-      return storageData[key]
+      return storageData[key] as number
     },
     setItem: (key: string, newValue: number) => {
       storageData[key] = newValue
@@ -67,7 +67,7 @@ describe('atomWithStorage (async)', () => {
       if (!(key in asyncStorageData)) {
         throw new Error('no value stored')
       }
-      return asyncStorageData[key]
+      return asyncStorageData[key] as number
     },
     setItem: async (key: string, newValue: number) => {
       await new Promise((r) => setTimeout(r, 10))
diff --git a/tsconfig.json b/tsconfig.json
index e950ca0bce..94235c5a3b 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,11 +1,11 @@
 {
   "compilerOptions": {
-    "target": "es2019",
+    "target": "esnext",
     "strict": true,
     "jsx": "react-jsx",
-    "allowSyntheticDefaultImports": true,
     "esModuleInterop": true,
     "moduleResolution": "node",
+    "noUncheckedIndexedAccess": true,
     "baseUrl": ".",
     "paths": {
       "jotai": ["./src/index.ts"]
diff --git a/yarn.lock b/yarn.lock
index 1f70e64f41..ddd96ec07a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -7114,16 +7114,16 @@ typedarray@^0.0.6:
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
   integrity sha1-hnrHTjhkGHsdPUfZlqeOxciDB3c=
 
-typescript@4.3.5:
-  version "4.3.5"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.3.5.tgz#4d1c37cc16e893973c45a06886b7113234f119f4"
-  integrity sha512-DqQgihaQ9cUrskJo9kIyW/+g0Vxsk8cDtZ52a3NGh0YNTfpUSArXSohyUGnvbPazEPLu398C0UxmKSOrPumUzA==
-
 typescript@^4.1.0-dev.20201026:
   version "4.4.2"
   resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.4.2.tgz#6d618640d430e3569a1dfb44f7d7e600ced3ee86"
   integrity sha512-gzP+t5W4hdy4c+68bfcv0t400HVJMMd2+H9B7gae1nQlBzCqvrXX+6GL/b3GAgyTH966pzrZ70/fRjwAtZksSQ==
 
+typescript@^4.4.3:
+  version "4.4.3"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.4.3.tgz#bdc5407caa2b109efd4f82fe130656f977a29324"
+  integrity sha512-4xfscpisVgqqDfPaJo5vkd+Qd/ItkoagnHpufr+i2QCHBsNYp+G7UAoyFl8aPtx879u38wPV65rZ8qbGZijalA==
+
 unbox-primitive@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/unbox-primitive/-/unbox-primitive-1.0.1.tgz#085e215625ec3162574dc8859abee78a59b14471"