diff --git a/handler/src/main/java/io/netty/handler/timeout/IdleStateEvent.java b/handler/src/main/java/io/netty/handler/timeout/IdleStateEvent.java
index 6617daa834..1a89798c78 100644
--- a/handler/src/main/java/io/netty/handler/timeout/IdleStateEvent.java
+++ b/handler/src/main/java/io/netty/handler/timeout/IdleStateEvent.java
@@ -25,16 +25,21 @@ import io.netty.util.internal.StringUtil;
  * A user event triggered by {@link IdleStateHandler} when a {@link Channel} is idle.
  */
 public class IdleStateEvent {
-    public static final IdleStateEvent FIRST_READER_IDLE_STATE_EVENT = new IdleStateEvent(IdleState.READER_IDLE, true);
-    public static final IdleStateEvent READER_IDLE_STATE_EVENT = new IdleStateEvent(IdleState.READER_IDLE, false);
-    public static final IdleStateEvent FIRST_WRITER_IDLE_STATE_EVENT = new IdleStateEvent(IdleState.WRITER_IDLE, true);
-    public static final IdleStateEvent WRITER_IDLE_STATE_EVENT = new IdleStateEvent(IdleState.WRITER_IDLE, false);
-    public static final IdleStateEvent FIRST_ALL_IDLE_STATE_EVENT = new IdleStateEvent(IdleState.ALL_IDLE, true);
-    public static final IdleStateEvent ALL_IDLE_STATE_EVENT = new IdleStateEvent(IdleState.ALL_IDLE, false);
+    public static final IdleStateEvent FIRST_READER_IDLE_STATE_EVENT =
+            new DefaultIdleStateEvent(IdleState.READER_IDLE, true);
+    public static final IdleStateEvent READER_IDLE_STATE_EVENT =
+            new DefaultIdleStateEvent(IdleState.READER_IDLE, false);
+    public static final IdleStateEvent FIRST_WRITER_IDLE_STATE_EVENT =
+            new DefaultIdleStateEvent(IdleState.WRITER_IDLE, true);
+    public static final IdleStateEvent WRITER_IDLE_STATE_EVENT =
+            new DefaultIdleStateEvent(IdleState.WRITER_IDLE, false);
+    public static final IdleStateEvent FIRST_ALL_IDLE_STATE_EVENT =
+            new DefaultIdleStateEvent(IdleState.ALL_IDLE, true);
+    public static final IdleStateEvent ALL_IDLE_STATE_EVENT =
+            new DefaultIdleStateEvent(IdleState.ALL_IDLE, false);
 
     private final IdleState state;
     private final boolean first;
-    private String strVal;
 
     /**
      * Constructor for sub-classes.
@@ -63,9 +68,20 @@ public class IdleStateEvent {
 
     @Override
     public String toString() {
-        if (strVal == null) {
-            strVal = StringUtil.simpleClassName(this) + "(" + state + (first ? ", first" : "") + ')';
+        return StringUtil.simpleClassName(this) + '(' + state + (first ? ", first" : "") + ')';
+    }
+
+    private static final class DefaultIdleStateEvent extends IdleStateEvent {
+        private final String representation;
+
+        DefaultIdleStateEvent(IdleState state, boolean first) {
+            super(state, first);
+            this.representation = "IdleStateEvent(" + state + (first ? ", first" : "") + ')';
+        }
+
+        @Override
+        public String toString() {
+            return representation;
         }
-        return strVal;
     }
 }