diff --git a/examples/clone3.rs b/examples/clone3.rs
new file mode 100644
index 00000000..0dfae416
--- /dev/null
+++ b/examples/clone3.rs
@@ -0,0 +1,14 @@
+fn main() {
+    let mut args = nc::clone_args_t::default();
+    let mut pid_fd: i32 = -1;
+    args.exit_signal = nc::SIGCHLD as u64;
+    args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
+    args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
+    let pid = unsafe { nc::clone3(&mut args) };
+    match pid {
+        Err(errno) => eprintln!("clone3() failed, err: {:?}", nc::strerror(errno)),
+        Ok(0) => println!("[child] pid"),
+        Ok(pid) => println!("[parent] pid: {pid:?}"),
+    }
+    assert!(pid.is_ok());
+}
diff --git a/src/calls/abort2.rs b/src/calls/abort2.rs
index d44609fa..6382ad42 100644
--- a/src/calls/abort2.rs
+++ b/src/calls/abort2.rs
@@ -1,5 +1,5 @@
 /// Abort process with diagnostics
-pub unsafe fn abort2(why: &str, args_len: i32, args: usize) -> ! {
+pub unsafe fn abort2(why: &str, args_len: i32, args: uinptr_t) -> ! {
     let why = CString::new(why);
     let why_ptr = why.as_ptr() as usize;
     let args_len = args_len as usize;
diff --git a/src/calls/add_key.rs b/src/calls/add_key.rs
index ae2f9c4d..15945d79 100644
--- a/src/calls/add_key.rs
+++ b/src/calls/add_key.rs
@@ -2,7 +2,7 @@
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
diff --git a/src/calls/clone.rs b/src/calls/clone.rs
index 8918b78c..601cc3b5 100644
--- a/src/calls/clone.rs
+++ b/src/calls/clone.rs
@@ -1,12 +1,11 @@
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
diff --git a/src/calls/clone3.rs b/src/calls/clone3.rs
index 1ad4c22e..f3a235f8 100644
--- a/src/calls/clone3.rs
+++ b/src/calls/clone3.rs
@@ -8,10 +8,11 @@
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
diff --git a/src/platform/linux-aarch64/call.rs b/src/platform/linux-aarch64/call.rs
index c56eaf4a..8ab7921d 100644
--- a/src/platform/linux-aarch64/call.rs
+++ b/src/platform/linux-aarch64/call.rs
@@ -72,7 +72,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -321,13 +321,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -351,11 +350,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
 
diff --git a/src/platform/linux-arm/call.rs b/src/platform/linux-arm/call.rs
index 48a3c90f..7768bbd1 100644
--- a/src/platform/linux-arm/call.rs
+++ b/src/platform/linux-arm/call.rs
@@ -91,7 +91,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -407,13 +407,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -437,11 +436,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
 
diff --git a/src/platform/linux-loongarch64/call.rs b/src/platform/linux-loongarch64/call.rs
index ed808dce..095fd92b 100644
--- a/src/platform/linux-loongarch64/call.rs
+++ b/src/platform/linux-loongarch64/call.rs
@@ -72,7 +72,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -278,13 +278,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -308,11 +307,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
 
diff --git a/src/platform/linux-mips/call.rs b/src/platform/linux-mips/call.rs
index 99ab177b..ed645e71 100644
--- a/src/platform/linux-mips/call.rs
+++ b/src/platform/linux-mips/call.rs
@@ -91,7 +91,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -449,13 +449,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -479,11 +478,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
 
diff --git a/src/platform/linux-mips64/call.rs b/src/platform/linux-mips64/call.rs
index 13a991f4..b6943901 100644
--- a/src/platform/linux-mips64/call.rs
+++ b/src/platform/linux-mips64/call.rs
@@ -91,7 +91,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -433,13 +433,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -463,11 +462,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
 
diff --git a/src/platform/linux-ppc64/call.rs b/src/platform/linux-ppc64/call.rs
index 83b49dc8..caa92794 100644
--- a/src/platform/linux-ppc64/call.rs
+++ b/src/platform/linux-ppc64/call.rs
@@ -91,7 +91,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -442,13 +442,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -472,11 +471,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
 
diff --git a/src/platform/linux-riscv64/call.rs b/src/platform/linux-riscv64/call.rs
index 5e6ef940..95b65295 100644
--- a/src/platform/linux-riscv64/call.rs
+++ b/src/platform/linux-riscv64/call.rs
@@ -72,7 +72,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -321,13 +321,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -351,11 +350,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
 
diff --git a/src/platform/linux-s390x/call.rs b/src/platform/linux-s390x/call.rs
index 83afcef8..12499c00 100644
--- a/src/platform/linux-s390x/call.rs
+++ b/src/platform/linux-s390x/call.rs
@@ -77,7 +77,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -424,13 +424,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -454,11 +453,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
 
diff --git a/src/platform/linux-x86/call.rs b/src/platform/linux-x86/call.rs
index e9a1916f..f32e1623 100644
--- a/src/platform/linux-x86/call.rs
+++ b/src/platform/linux-x86/call.rs
@@ -77,7 +77,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -434,13 +434,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -464,11 +463,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }
 
diff --git a/src/platform/linux-x86_64/call.rs b/src/platform/linux-x86_64/call.rs
index 7165c163..db6cdd63 100644
--- a/src/platform/linux-x86_64/call.rs
+++ b/src/platform/linux-x86_64/call.rs
@@ -91,7 +91,7 @@ pub unsafe fn acct<P: AsRef<Path>>(filename: P) -> Result<(), Errno> {
 pub unsafe fn add_key<P: AsRef<Path>>(
     type_: P,
     description: P,
-    payload: usize,
+    payload: uintptr_t,
     plen: size_t,
     dest_keyring: key_serial_t,
 ) -> Result<key_serial_t, Errno> {
@@ -432,13 +432,12 @@ pub unsafe fn clock_settime(which_clock: clockid_t, tp: &timespec_t) -> Result<(
 
 /// Create a child process.
 pub unsafe fn clone(
-    clone_flags: i32,
+    clone_flags: usize,
     newsp: usize,
     parent_tid: &mut i32,
     child_tid: &mut i32,
     tls: usize,
 ) -> Result<pid_t, Errno> {
-    let clone_flags = clone_flags as usize;
     let parent_tid_ptr = parent_tid as *mut i32 as usize;
     let child_tid_ptr = child_tid as *mut i32 as usize;
     syscall5(
@@ -462,11 +461,12 @@ pub unsafe fn clone(
 /// args.exit_signal = nc::SIGCHLD as u64;
 /// args.pidfd = &mut pid_fd as *mut i32 as usize as u64;
 /// args.flags = nc::CLONE_PIDFD as u64 | nc::CLONE_PARENT_SETTID as u64;
-/// let pid = unsafe { nc::clone3(&mut args, core::mem::size_of::<nc::clone_args_t>()) };
+/// let pid = unsafe { nc::clone3(&mut args) };
 /// assert!(pid.is_ok());
 /// ```
-pub unsafe fn clone3(cl_args: &mut clone_args_t, size: size_t) -> Result<pid_t, Errno> {
+pub unsafe fn clone3(cl_args: &mut clone_args_t) -> Result<pid_t, Errno> {
     let cl_args_ptr = cl_args as *mut clone_args_t as usize;
+    let size = core::mem::size_of::<clone_args_t>();
     syscall2(SYS_CLONE3, cl_args_ptr, size).map(|ret| ret as pid_t)
 }