diff --git a/include/packet_writer.h b/include/packet_writer.h
index 28258f5..b015a90 100644
--- a/include/packet_writer.h
+++ b/include/packet_writer.h
@@ -98,6 +98,18 @@ public:
      */
     void write(PDU &pdu);
     
+    /**
+     * \brief Writes a PDU to this file. 
+     * 
+     * The template parameter T must at some point yield a PDU& after
+     * applying operator* one or more than one time. This accepts both
+     * raw and smartpointers.
+     */
+    template<typename T>
+    void write(T &pdu) {
+        write(Utils::dereference_until_pdu(pdu));
+    }
+    
     /**
      * \brief Writes all the PDUs in the range [start, end)
      * \param start A forward iterator pointing to the first PDU
diff --git a/src/ip.cpp b/src/ip.cpp
index 38dee63..97ee561 100644
--- a/src/ip.cpp
+++ b/src/ip.cpp
@@ -378,6 +378,7 @@ void IP::prepare_for_serialize(const PDU *parent) {
 void IP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU* parent) {
     uint32_t my_sz = header_size();
     assert(total_sz >= my_sz);
+    check(0);
     if(inner_pdu()) {
         uint32_t new_flag;
         switch(inner_pdu()->pdu_type()) {
@@ -415,12 +416,12 @@ void IP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU* pare
         ptr_buffer = write_option(*it, ptr_buffer);
     memset(buffer + sizeof(_ip) + _options_size, 0, _padded_options_size - _options_size);
 
-    if(parent && !_ip.check) {
+    if(parent) {
         uint32_t checksum = Utils::do_checksum(buffer, buffer + sizeof(_ip) + _padded_options_size);
         while (checksum >> 16)
             checksum = (checksum & 0xffff) + (checksum >> 16);
-        ((iphdr*)buffer)->check = Endian::host_to_be<uint16_t>(~checksum);
-        this->check(0);
+        check(~checksum);
+        ((iphdr*)buffer)->check = _ip.check;
     }
 }
 
diff --git a/src/tcp.cpp b/src/tcp.cpp
index 05a806d..f5a65b3 100644
--- a/src/tcp.cpp
+++ b/src/tcp.cpp
@@ -284,6 +284,7 @@ uint32_t TCP::header_size() const {
 void TCP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *parent) {
     assert(total_sz >= header_size());
     uint8_t *tcp_start = buffer;
+    check(0);
     buffer += sizeof(tcphdr);
     _tcp.doff = (sizeof(tcphdr) + _total_options_size) / sizeof(uint32_t);
     for(options_type::iterator it = _options.begin(); it != _options.end(); ++it)
@@ -299,34 +300,30 @@ void TCP::write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *par
 
     memcpy(tcp_start, &_tcp, sizeof(tcphdr));
 
-    if(!_tcp.check) {
-        const Tins::IP *ip_packet = dynamic_cast<const Tins::IP*>(parent);
-        if(ip_packet) {
-            uint32_t checksum = Utils::pseudoheader_checksum(ip_packet->src_addr(),  
-                                                             ip_packet->dst_addr(), 
-                                                             size(), Constants::IP::PROTO_TCP) +
-                                Utils::do_checksum(tcp_start, tcp_start + total_sz);
+    const Tins::IP *ip_packet = dynamic_cast<const Tins::IP*>(parent);
+    if(ip_packet) {
+        uint32_t checksum = Utils::pseudoheader_checksum(ip_packet->src_addr(),  
+                                                         ip_packet->dst_addr(), 
+                                                         size(), Constants::IP::PROTO_TCP) +
+                            Utils::do_checksum(tcp_start, tcp_start + total_sz);
+        while (checksum >> 16)
+            checksum = (checksum & 0xffff) + (checksum >> 16);
+        check(~checksum);
+        ((tcphdr*)tcp_start)->check = _tcp.check;
+    }
+    else {
+        const Tins::IPv6 *ipv6_packet = dynamic_cast<const Tins::IPv6*>(parent);
+        if(ipv6_packet) {
+            uint32_t checksum = Utils::pseudoheader_checksum(ipv6_packet->src_addr(),  
+                                                         ipv6_packet->dst_addr(), 
+                                                         size(), Constants::IP::PROTO_TCP) +
+                                        Utils::do_checksum(tcp_start, tcp_start + total_sz);
             while (checksum >> 16)
                 checksum = (checksum & 0xffff) + (checksum >> 16);
-            
-            ((tcphdr*)tcp_start)->check = Endian::host_to_be<uint16_t>(~checksum);
-        }
-        else {
-            const Tins::IPv6 *ipv6_packet = dynamic_cast<const Tins::IPv6*>(parent);
-            if(ipv6_packet) {
-                uint32_t checksum = Utils::pseudoheader_checksum(ipv6_packet->src_addr(),  
-                                                             ipv6_packet->dst_addr(), 
-                                                             size(), Constants::IP::PROTO_TCP) +
-                                            Utils::do_checksum(tcp_start, tcp_start + total_sz);
-                while (checksum >> 16)
-                    checksum = (checksum & 0xffff) + (checksum >> 16);
-                
-                ((tcphdr*)tcp_start)->check = Endian::host_to_be<uint16_t>(~checksum);
-            }
+            check(~checksum);
+            ((tcphdr*)tcp_start)->check = _tcp.check;
         }
     }
-    
-    _tcp.check = 0;
 }
 
 const TCP::option *TCP::search_option(OptionTypes opt) const {