diff --git a/src/useEvent.ts b/src/useEvent.ts
index 3bd51b4e..0f30b949 100644
--- a/src/useEvent.ts
+++ b/src/useEvent.ts
@@ -1,4 +1,5 @@
 import {useEffect} from 'react';
+import {isClient} from './util';
 
 export interface ListenerType1 {
   addEventListener (name: string, handler: (event?: any) => void, ...args: any[]);
@@ -12,7 +13,7 @@ export interface ListenerType2 {
 
 export type UseEventTarget = ListenerType1 | ListenerType2;
 
-const defaultTarget = typeof window === 'object' ? window : null;
+const defaultTarget = isClient ? window : null;
 
 const useEvent = (name: string, handler?: null | undefined | ((event?: any) => void), target: null | UseEventTarget = defaultTarget, options?: any) => {
   useEffect(() => {
diff --git a/src/useLocalStorage.ts b/src/useLocalStorage.ts
index 78a9671c..24d95a22 100644
--- a/src/useLocalStorage.ts
+++ b/src/useLocalStorage.ts
@@ -1,6 +1,5 @@
 import {useState, useEffect} from 'react';
-
-const isClient = typeof window === 'object';
+import {isClient} from './util';
 
 const useLocalStorage = <T>(key: string, initialValue?: T, raw?: boolean): [T, (value: T) => void] => {
   if (!isClient) {
diff --git a/src/useSessionStorage.ts b/src/useSessionStorage.ts
index 8621bd99..2c09310a 100644
--- a/src/useSessionStorage.ts
+++ b/src/useSessionStorage.ts
@@ -1,6 +1,5 @@
 import {useState, useEffect} from 'react';
-
-const isClient = typeof window === 'object';
+import {isClient} from './util';
 
 const useSessionStorage = <T>(key: string, initialValue?: T, raw?: boolean): [T, (value: T) => void] => {
   if (!isClient) {
diff --git a/src/useSize.tsx b/src/useSize.tsx
index 49c9882b..3c2baa65 100644
--- a/src/useSize.tsx
+++ b/src/useSize.tsx
@@ -1,8 +1,8 @@
 import * as React from 'react';
+import {isClient} from './util';
 
 const {useState, useEffect, useRef} = React;
 
-const isClient = typeof window === 'object';
 const DRAF = (callback: () => void) => setTimeout(callback, 35);
 
 export type Element = ((state: State) => React.ReactElement<any>) | React.ReactElement<any>;
diff --git a/src/useWindowSize.ts b/src/useWindowSize.ts
index 2e115a92..7ed04c75 100644
--- a/src/useWindowSize.ts
+++ b/src/useWindowSize.ts
@@ -1,6 +1,5 @@
 import {useState, useEffect} from 'react';
-
-const isClient = typeof window === 'object';
+import {isClient} from './util';
 
 const useWindowSize = (initialWidth = Infinity, initialHeight = Infinity) => {
   const [state, setState] = useState<{width: number, height: number}>({