diff --git a/mqttpacket.cpp b/mqttpacket.cpp
index 8662f4a..0423adf 100644
--- a/mqttpacket.cpp
+++ b/mqttpacket.cpp
@@ -1012,6 +1012,8 @@ void MqttPacket::handleUnsubscribe()
 
 void MqttPacket::parsePublishData()
 {
+    setPosToDataStart();
+
     publishData.retain = (first_byte & 0b00000001);
     const bool duplicate = !!(first_byte & 0b00001000);
     publishData.qos = (first_byte & 0b00000110) >> 1;
@@ -1256,6 +1258,11 @@ void MqttPacket::calculateRemainingLength()
     this->remainingLength = bites.size();
 }
 
+void MqttPacket::setPosToDataStart()
+{
+    this->pos = this->fixed_header_length;
+}
+
 bool MqttPacket::atEnd() const
 {
     assert(pos <= bites.size());
diff --git a/mqttpacket.h b/mqttpacket.h
index ec024f6..41bfad1 100644
--- a/mqttpacket.h
+++ b/mqttpacket.h
@@ -85,7 +85,7 @@ class MqttPacket
     std::string readBytesToString(bool validateUtf8 = true, bool alsoCheckInvalidPublishChars = false);
 
     void calculateRemainingLength();
-
+    void setPosToDataStart();
     bool atEnd() const;
 
     MqttPacket(const MqttPacket &other) = delete;