diff --git a/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttDecoder.java b/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttDecoder.java
index 16052b4f52..1f1a81c6c1 100644
--- a/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttDecoder.java
+++ b/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttDecoder.java
@@ -204,7 +204,7 @@ public class MqttDecoder extends ReplayingDecoder<DecoderState> {
     private static Result<MqttConnectVariableHeader> decodeConnectionVariableHeader(ByteBuf buffer) {
         final Result<String> protoString = decodeString(buffer);
         if (!PROTOCOL_NAME.equals(protoString.value)) {
-            throw new DecoderException("missing " + PROTOCOL_NAME + " signature");
+            throw new MqttUnacceptableProtocolVersionException("missing " + PROTOCOL_NAME + " signature");
         }
 
         int numberOfBytesConsumed = protoString.numberOfBytesConsumed;
@@ -322,7 +322,7 @@ public class MqttDecoder extends ReplayingDecoder<DecoderState> {
         final Result<String> decodedClientId = decodeString(buffer);
         final String decodedClientIdValue = decodedClientId.value;
         if (!isValidClientId(decodedClientIdValue)) {
-            throw new DecoderException("invalid clientIdentifier: " + decodedClientIdValue);
+            throw new MqttIdentifierRejectedException("invalid clientIdentifier: " + decodedClientIdValue);
         }
         int numberOfBytesConsumed = decodedClientId.numberOfBytesConsumed;
 
diff --git a/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttIdentifierRejectedException.java b/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttIdentifierRejectedException.java
new file mode 100644
index 0000000000..60fbe92a65
--- /dev/null
+++ b/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttIdentifierRejectedException.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2014 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.mqtt;
+
+import io.netty.handler.codec.DecoderException;
+
+/**
+ * A {@link MqttIdentifierRejectedException} which is thrown when a CONNECT request contains invalid client identifier.
+ */
+public class MqttIdentifierRejectedException extends DecoderException {
+
+    private static final long serialVersionUID = -1323503322689614981L;
+
+    /**
+     * Creates a new instance
+     */
+    public MqttIdentifierRejectedException() { }
+
+    /**
+     * Creates a new instance
+     */
+    public MqttIdentifierRejectedException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    /**
+     * Creates a new instance
+     */
+    public MqttIdentifierRejectedException(String message) {
+        super(message);
+    }
+
+    /**
+     * Creates a new instance
+     */
+    public MqttIdentifierRejectedException(Throwable cause) {
+        super(cause);
+    }
+
+}
diff --git a/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttUnacceptableProtocolVersionException.java b/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttUnacceptableProtocolVersionException.java
new file mode 100644
index 0000000000..26b3b9cbc7
--- /dev/null
+++ b/codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttUnacceptableProtocolVersionException.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2014 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.mqtt;
+
+import io.netty.handler.codec.DecoderException;
+
+/**
+ * A {@link MqttUnacceptableProtocolVersionException} which is thrown when
+ * a CONNECT request contains unacceptable protocol version.
+ */
+public class MqttUnacceptableProtocolVersionException extends DecoderException {
+
+    private static final long serialVersionUID = 4914652213232455749L;
+
+    /**
+     * Creates a new instance
+     */
+    public MqttUnacceptableProtocolVersionException() { }
+
+    /**
+     * Creates a new instance
+     */
+    public MqttUnacceptableProtocolVersionException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    /**
+     * Creates a new instance
+     */
+    public MqttUnacceptableProtocolVersionException(String message) {
+        super(message);
+    }
+
+    /**
+     * Creates a new instance
+     */
+    public MqttUnacceptableProtocolVersionException(Throwable cause) {
+        super(cause);
+    }
+
+}