diff --git a/handler/src/main/java/io/netty/handler/timeout/IdleStateHandler.java b/handler/src/main/java/io/netty/handler/timeout/IdleStateHandler.java
index ee80dcf7e0..c36ef42f5c 100644
--- a/handler/src/main/java/io/netty/handler/timeout/IdleStateHandler.java
+++ b/handler/src/main/java/io/netty/handler/timeout/IdleStateHandler.java
@@ -25,6 +25,7 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOutboundBuffer;
 import io.netty.channel.ChannelPromise;
+import io.netty.util.internal.ObjectUtil;
 
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
@@ -190,9 +191,7 @@ public class IdleStateHandler extends ChannelDuplexHandler {
     public IdleStateHandler(boolean observeOutput,
             long readerIdleTime, long writerIdleTime, long allIdleTime,
             TimeUnit unit) {
-        if (unit == null) {
-            throw new NullPointerException("unit");
-        }
+        ObjectUtil.checkNotNull(unit, "unit");
 
         this.observeOutput = observeOutput;