diff --git a/codec-http/src/test/java/io/netty/handler/codec/http/HttpHeadersTest.java b/codec-http/src/test/java/io/netty/handler/codec/http/HttpHeadersTest.java
index ab3dce49d1..2f44f6dd5b 100644
--- a/codec-http/src/test/java/io/netty/handler/codec/http/HttpHeadersTest.java
+++ b/codec-http/src/test/java/io/netty/handler/codec/http/HttpHeadersTest.java
@@ -79,9 +79,11 @@ public class HttpHeadersTest {
         headers.add(headers);
     }
 
-    @Test(expected = IllegalArgumentException.class)
-    public void testSetSelf() {
+    @Test
+    public void testSetSelfIsNoOp() {
         HttpHeaders headers = new DefaultHttpHeaders(false);
+        headers.add("name", "value");
         headers.set(headers);
+        assertEquals(1, headers.size());
     }
 }
diff --git a/codec/src/main/java/io/netty/handler/codec/DefaultHeaders.java b/codec/src/main/java/io/netty/handler/codec/DefaultHeaders.java
index 89fe19561e..cc9b6a2db3 100644
--- a/codec/src/main/java/io/netty/handler/codec/DefaultHeaders.java
+++ b/codec/src/main/java/io/netty/handler/codec/DefaultHeaders.java
@@ -543,7 +543,7 @@ public class DefaultHeaders<K, V, T extends Headers<K, V, T>> implements Headers
     public T set(Headers<? extends K, ? extends V, ?> headers) {
         checkNotNull(headers, "headers");
         if (headers == this) {
-            throw new IllegalArgumentException("can't add to itself.");
+            return thisT();
         }
         clear();
         if (headers instanceof DefaultHeaders) {
diff --git a/codec/src/test/java/io/netty/handler/codec/DefaultHeadersTest.java b/codec/src/test/java/io/netty/handler/codec/DefaultHeadersTest.java
index 5f8472c385..ceee0b80be 100644
--- a/codec/src/test/java/io/netty/handler/codec/DefaultHeadersTest.java
+++ b/codec/src/test/java/io/netty/handler/codec/DefaultHeadersTest.java
@@ -390,9 +390,11 @@ public class DefaultHeadersTest {
         headers.add(headers);
     }
 
-    @Test(expected = IllegalArgumentException.class)
-    public void testSetSelf() {
+    @Test
+    public void testSetSelfIsNoOp() {
         TestDefaultHeaders headers = newInstance();
+        headers.add("name", "value");
         headers.set(headers);
+        assertEquals(1, headers.size());
     }
 }