diff --git a/internal/lib/os/wait_waitid.go b/internal/lib/os/wait_waitid.go
index 0c89c81b..301254b3 100644
--- a/internal/lib/os/wait_waitid.go
+++ b/internal/lib/os/wait_waitid.go
@@ -10,10 +10,10 @@
 package os
 
 import (
+	"syscall"
 	_ "unsafe"
 
 	"github.com/goplus/llgo/c"
-	"github.com/goplus/llgo/c/syscall"
 )
 
 const _P_PID = 1
diff --git a/internal/lib/syscall/exec_libc.go b/internal/lib/syscall/exec_libc.go
index 44557867..1c38a19a 100644
--- a/internal/lib/syscall/exec_libc.go
+++ b/internal/lib/syscall/exec_libc.go
@@ -11,6 +11,8 @@ package syscall
 import (
 	"runtime"
 	"unsafe"
+
+	"github.com/goplus/llgo/c"
 )
 
 type SysProcAttr struct {
@@ -77,8 +79,8 @@ func init() {
 // split the stack, or acquire mutexes). We can't call RawSyscall
 // because it's not safe even for BSD-subsystem calls.
 //
-//go:norace
-func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr *ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {
+// func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr *ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {
+func forkAndExecInChild(argv0 *c.Char, argv, envv **c.Char, chroot, dir *c.Char, attr *ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {
 	// Declare all variables at top in case any
 	// declarations require heap allocation (e.g., err1).
 	var (
diff --git a/internal/lib/syscall/exec_libc2.go b/internal/lib/syscall/exec_libc2.go
index 61b2c3b3..4c45b80b 100644
--- a/internal/lib/syscall/exec_libc2.go
+++ b/internal/lib/syscall/exec_libc2.go
@@ -52,8 +52,6 @@ func runtime_AfterForkInChild()
 // For the same reason compiler does not race instrument it.
 // The calls to rawSyscall are okay because they are assembly
 // functions that do not grow the stack.
-//
-//go:norace
 func forkAndExecInChild(argv0 *c.Char, argv, envv **c.Char, chroot, dir *c.Char, attr *ProcAttr, sys *SysProcAttr, pipe int) (pid int, err1 Errno) {
 	// Declare all variables at top in case any
 	// declarations require heap allocation (e.g., err1).
diff --git a/internal/lib/syscall/exec_linux.go b/internal/lib/syscall/exec_linux.go
index c66e820f..fb93fce3 100644
--- a/internal/lib/syscall/exec_linux.go
+++ b/internal/lib/syscall/exec_linux.go
@@ -6,6 +6,8 @@
 
 package syscall
 
+import "github.com/goplus/llgo/c"
+
 // Linux unshare/clone/clone2/clone3 flags, architecture-independent,
 // copied from linux/sched.h.
 const (
@@ -119,8 +121,8 @@ func runtime_AfterForkInChild()
 // The calls to RawSyscall are okay because they are assembly
 // functions that do not grow the stack.
 //
-//go:norace
-func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr *ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {
+// func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr *ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {
+func forkAndExecInChild(argv0 *c.Char, argv, envv **c.Char, chroot, dir *c.Char, attr *ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {
 	/* TODO(xsw):
 	// Set up and fork. This returns immediately in the parent or
 	// if there's an error.
diff --git a/internal/lib/syscall/syscall_linux.go b/internal/lib/syscall/syscall_linux.go
index 3b643db2..7c4c2a59 100644
--- a/internal/lib/syscall/syscall_linux.go
+++ b/internal/lib/syscall/syscall_linux.go
@@ -15,6 +15,7 @@ import (
 	_ "unsafe"
 
 	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/c/syscall"
 )
 
 // -----------------------------------------------------------------------------
@@ -78,6 +79,15 @@ func (w WaitStatus) TrapCause() int {
 }
 */
 
+func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
+	var status c.Int
+	wpid, err = wait4(pid, &status, options, rusage)
+	if wstatus != nil {
+		*wstatus = WaitStatus(status)
+	}
+	return
+}
+
 // -----------------------------------------------------------------------------
 
 // int pipe2(int pipefd[2], int flags);
@@ -85,13 +95,9 @@ func (w WaitStatus) TrapCause() int {
 //go:linkname pipe2 C.pipe2
 func pipe2(pipefd *[2]c.Int, flags c.Int) c.Int
 
-func Pipe(p []int) error {
-	return Pipe2(p, 0)
-}
-
 func Pipe2(p []int, flags int) error {
 	if len(p) != 2 {
-		return EINVAL
+		return Errno(syscall.EINVAL)
 	}
 	var pp [2]c.Int
 	ret := pipe2(&pp, c.Int(flags))