diff --git a/examples/async_icmp_socket.rs b/examples/async_icmp_socket.rs
index d948357..93fa3cc 100644
--- a/examples/async_icmp_socket.rs
+++ b/examples/async_icmp_socket.rs
@@ -98,7 +98,6 @@ async fn main() -> std::io::Result<()> {
                 .icmp_code(icmp::echo_request::IcmpCodes::NoCode)
                 .echo_fields(id, seq)
                 .payload(Bytes::from_static(b"ping"))
-                .calculate_checksum()
                 .to_bytes();
             let target = SocketAddr::new(IpAddr::V4(addr), 0);
             let _ = socket.send_to(&pkt, target).await;
diff --git a/examples/icmp_ping.rs b/examples/icmp_ping.rs
index 076fe5e..431b280 100644
--- a/examples/icmp_ping.rs
+++ b/examples/icmp_ping.rs
@@ -70,7 +70,6 @@ fn main() {
             .icmp_code(icmp::echo_request::IcmpCodes::NoCode)
             .echo_fields(0x1234, 0x1)
             .payload(Bytes::from_static(b"hello"))
-            .calculate_checksum()
             .build()
             .to_bytes(),
         (IpAddr::V6(src), IpAddr::V6(dst)) => Icmpv6PacketBuilder::new(src, dst)
@@ -78,7 +77,6 @@ fn main() {
             .icmpv6_code(icmpv6::echo_request::Icmpv6Codes::NoCode)
             .echo_fields(0x1234, 0x1)
             .payload(Bytes::from_static(b"hello"))
-            .calculate_checksum()
             .build()
             .to_bytes(),
         _ => panic!("Source and destination IP version mismatch"),
diff --git a/examples/icmp_socket.rs b/examples/icmp_socket.rs
index aa33741..a666057 100644
--- a/examples/icmp_socket.rs
+++ b/examples/icmp_socket.rs
@@ -56,14 +56,12 @@ fn main() -> std::io::Result<()> {
             .icmp_code(icmp::echo_request::IcmpCodes::NoCode)
             .echo_fields(0x1234, 1)
             .payload(Bytes::from_static(b"hello"))
-            .calculate_checksum()
             .to_bytes(),
         (IpAddr::V6(src), IpAddr::V6(dst)) => Icmpv6PacketBuilder::new(src, dst)
             .icmpv6_type(nex_packet::icmpv6::Icmpv6Type::EchoRequest)
             .icmpv6_code(icmpv6::echo_request::Icmpv6Codes::NoCode)
             .echo_fields(0x1234, 1)
             .payload(Bytes::from_static(b"hello"))
-            .calculate_checksum()
             .to_bytes(),
         _ => unreachable!(),
     };
diff --git a/examples/tcp_ping.rs b/examples/tcp_ping.rs
index 7e05b43..1bd4810 100644
--- a/examples/tcp_ping.rs
+++ b/examples/tcp_ping.rs
@@ -106,7 +106,7 @@ fn main() {
     }
 
     // Packet builder for TCP SYN
-    let tcp_packet = TcpPacketBuilder::new()
+    let tcp_packet = TcpPacketBuilder::new(src_ip, dst_ip)
         .source(53443)
         .destination(target_socket.port())
         .flags(TcpFlags::SYN)
@@ -118,7 +118,6 @@ fn main() {
             TcpOptionPacket::nop(),
             TcpOptionPacket::wscale(7),
         ])
-        .calculate_checksum(&src_ip, &dst_ip)
         .build();
 
     let ip_packet: Bytes;
diff --git a/examples/udp_ping.rs b/examples/udp_ping.rs
index 929acf2..580e785 100644
--- a/examples/udp_ping.rs
+++ b/examples/udp_ping.rs
@@ -65,10 +65,9 @@ fn main() {
             .expect("No global IPv6 address on interface"),
     };
 
-    let udp_packet = UdpPacketBuilder::new()
+    let udp_packet = UdpPacketBuilder::new(src_ip, target_ip)
         .source(SRC_PORT)
         .destination(DST_PORT)
-        .calculate_checksum(&src_ip, &target_ip)
         .build();
 
     let ip_packet: Bytes = match (src_ip, target_ip) {
diff --git a/nex-packet/src/builder/icmp.rs b/nex-packet/src/builder/icmp.rs
index 1d2caff..690f75b 100644
--- a/nex-packet/src/builder/icmp.rs
+++ b/nex-packet/src/builder/icmp.rs
@@ -1,7 +1,7 @@
 use std::net::Ipv4Addr;
 
 use crate::{
-    icmp::{self, checksum, IcmpCode, IcmpHeader, IcmpPacket, IcmpType},
+    icmp::{self, IcmpCode, IcmpHeader, IcmpPacket, IcmpType},
     packet::Packet,
 };
 use bytes::{BufMut, Bytes, BytesMut};
@@ -62,15 +62,15 @@ impl IcmpPacketBuilder {
         self
     }
 
+    /// Calculate the checksum and set it in the header
     pub fn calculate_checksum(mut self) -> Self {
-        // Calculate the checksum and set it in the header
-        self.packet.header.checksum = checksum(&self.packet);
+        self.packet.header.checksum = icmp::checksum(&self.packet);
         self
     }
 
     /// Return an `IcmpPacket` with checksum computed
     pub fn build(mut self) -> IcmpPacket {
-        self.packet.header.checksum = checksum(&self.packet);
+        self.packet.header.checksum = icmp::checksum(&self.packet);
         self.packet
     }
 
diff --git a/nex-packet/src/builder/icmpv6.rs b/nex-packet/src/builder/icmpv6.rs
index 7d613d7..636517e 100644
--- a/nex-packet/src/builder/icmpv6.rs
+++ b/nex-packet/src/builder/icmpv6.rs
@@ -1,7 +1,7 @@
 use std::net::Ipv6Addr;
 
 use crate::{
-    icmpv6::{self, checksum, Icmpv6Code, Icmpv6Header, Icmpv6Packet, Icmpv6Type},
+    icmpv6::{self, Icmpv6Code, Icmpv6Header, Icmpv6Packet, Icmpv6Type},
     packet::Packet,
 };
 use bytes::{BufMut, Bytes, BytesMut};
@@ -58,15 +58,15 @@ impl Icmpv6PacketBuilder {
         self
     }
 
+    /// Calculate the checksum and set it in the header
     pub fn calculate_checksum(mut self) -> Self {
-        // Calculate the checksum and set it in the header
-        self.packet.header.checksum = checksum(&self.packet, &self.source, &self.destination);
+        self.packet.header.checksum = icmpv6::checksum(&self.packet, &self.source, &self.destination);
         self
     }
 
     /// Return an `Icmpv6Packet` with checksum computed
     pub fn build(mut self) -> Icmpv6Packet {
-        self.packet.header.checksum = checksum(&self.packet, &self.source, &self.destination);
+        self.packet.header.checksum = icmpv6::checksum(&self.packet, &self.source, &self.destination);
         self.packet
     }
 
diff --git a/nex-packet/src/builder/ipv4.rs b/nex-packet/src/builder/ipv4.rs
index 4395d4f..526cfbc 100644
--- a/nex-packet/src/builder/ipv4.rs
+++ b/nex-packet/src/builder/ipv4.rs
@@ -100,7 +100,6 @@ impl Ipv4PacketBuilder {
     pub fn build(mut self) -> Ipv4Packet {
         let total_length = self.packet.header_len() + self.packet.payload_len();
         self.packet.header.total_length = total_length as u16be;
-        self.packet.header.checksum = 0;
         self.packet.header.checksum = crate::ipv4::checksum(&self.packet);
         self.packet
     }
diff --git a/nex-packet/src/builder/tcp.rs b/nex-packet/src/builder/tcp.rs
index c18627e..302336f 100644
--- a/nex-packet/src/builder/tcp.rs
+++ b/nex-packet/src/builder/tcp.rs
@@ -7,13 +7,17 @@ use bytes::Bytes;
 /// Builder for constructing TCP packets
 #[derive(Debug, Clone)]
 pub struct TcpPacketBuilder {
+    src_ip: IpAddr,
+    dst_ip: IpAddr,
     packet: TcpPacket,
 }
 
 impl TcpPacketBuilder {
     /// Create a new builder
-    pub fn new() -> Self {
+    pub fn new(src_ip: IpAddr, dst_ip: IpAddr) -> Self {
         Self {
+            src_ip,
+            dst_ip,
             packet: TcpPacket {
                 header: TcpHeader {
                     source: 0,
@@ -89,29 +93,33 @@ impl TcpPacketBuilder {
         self
     }
 
-    pub fn calculate_checksum(mut self, src_ip: &IpAddr, dst_ip: &IpAddr) -> Self {
-        // Calculate the checksum and set it in the header
-        self.packet.header.checksum = crate::tcp::checksum(&self.packet, src_ip, dst_ip);
+    /// Calculate the checksum and set it in the header
+    pub fn calculate_checksum(mut self) -> Self {
+        self.packet.header.checksum = crate::tcp::checksum(&self.packet, &self.src_ip, &self.dst_ip);
         self
     }
-    pub fn build(self) -> TcpPacket {
+    /// Build the packet with checksum computed
+    pub fn build(mut self) -> TcpPacket {
+        self.packet.header.checksum = crate::tcp::checksum(&self.packet, &self.src_ip, &self.dst_ip);
         self.packet
     }
-
+    /// Serialize the packet into bytes with checksum computed
     pub fn to_bytes(self) -> Bytes {
-        self.packet.to_bytes()
+        self.build().to_bytes()
     }
 }
 
 #[cfg(test)]
 mod tests {
+    use std::net::Ipv4Addr;
+
     use super::*;
     use crate::tcp::TcpFlags;
     use bytes::Bytes;
 
     #[test]
     fn tcp_builder_basic() {
-        let pkt = TcpPacketBuilder::new()
+        let pkt = TcpPacketBuilder::new(IpAddr::V4(Ipv4Addr::new(192, 168, 1, 100)), IpAddr::V4(Ipv4Addr::new(192, 168, 1, 1)))
             .source(1234)
             .destination(80)
             .sequence(1)
diff --git a/nex-packet/src/builder/udp.rs b/nex-packet/src/builder/udp.rs
index f55d11d..d7d807e 100644
--- a/nex-packet/src/builder/udp.rs
+++ b/nex-packet/src/builder/udp.rs
@@ -7,13 +7,17 @@ use bytes::Bytes;
 /// Builder for constructing UDP packets
 #[derive(Debug, Clone)]
 pub struct UdpPacketBuilder {
+    src_ip: IpAddr,
+    dst_ip: IpAddr,
     packet: UdpPacket,
 }
 
 impl UdpPacketBuilder {
     /// Create a new builder
-    pub fn new() -> Self {
+    pub fn new(src_ip: IpAddr, dst_ip: IpAddr) -> Self {
         Self {
+            src_ip,
+            dst_ip,
             packet: UdpPacket {
                 header: UdpHeader {
                     source: 0,
@@ -50,21 +54,24 @@ impl UdpPacketBuilder {
         self
     }
 
-    pub fn calculate_checksum(mut self, src_ip: &IpAddr, dst_ip: &IpAddr) -> Self {
+    /// Calculate the checksum and set it in the header
+    pub fn calculate_checksum(mut self) -> Self {
         // Calculate the checksum and set it in the header
-        self.packet.header.checksum = crate::udp::checksum(&self.packet, src_ip, dst_ip);
+        self.packet.header.checksum = crate::udp::checksum(&self.packet, &self.src_ip, &self.dst_ip);
         self
     }
 
-    /// Build the packet
+    /// Build the packet with checksum computed
     pub fn build(mut self) -> UdpPacket {
         // Automatically compute the length
         let total_len = UDP_HEADER_LEN + self.packet.payload.len();
         self.packet.header.length = (total_len as u16).into();
+        // Calculate the checksum
+        self.packet.header.checksum = crate::udp::checksum(&self.packet, &self.src_ip, &self.dst_ip);
         self.packet
     }
 
-    /// Serialize the packet into bytes
+    /// Serialize the packet into bytes with checksum computed
     pub fn to_bytes(self) -> Bytes {
         self.build().to_bytes()
     }
@@ -79,12 +86,14 @@ impl UdpPacketBuilder {
 
 #[cfg(test)]
 mod tests {
+    use std::net::Ipv4Addr;
+
     use super::*;
     use bytes::Bytes;
 
     #[test]
     fn udp_builder_sets_length() {
-        let pkt = UdpPacketBuilder::new()
+        let pkt = UdpPacketBuilder::new(IpAddr::V4(Ipv4Addr::new(192, 168, 1, 100)), IpAddr::V4(Ipv4Addr::new(192, 168, 1, 1)))
             .source(1)
             .destination(2)
             .payload(Bytes::from_static(&[1, 2, 3]))