diff --git a/src/syscall/exec_bsd.go b/src/syscall/exec_bsd.go
index 4762ae751a..3e4c6f9d62 100644
--- a/src/syscall/exec_bsd.go
+++ b/src/syscall/exec_bsd.go
@@ -184,6 +184,8 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	if pipe < nextfd {
 		if runtime.GOOS == "netbsd" || (runtime.GOOS == "openbsd" && runtime.GOARCH == "mips64") {
 			_, _, err1 = RawSyscall(_SYS_DUP3, uintptr(pipe), uintptr(nextfd), O_CLOEXEC)
+		} else if runtime.GOOS == "dragonfly" {
+			_, _, err1 = RawSyscall(SYS_FCNTL, uintptr(pipe), _F_DUP2FD_CLOEXEC, uintptr(nextfd))
 		} else {
 			_, _, err1 = RawSyscall(SYS_DUP2, uintptr(pipe), uintptr(nextfd), 0)
 			if err1 != 0 {
@@ -204,6 +206,8 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 			}
 			if runtime.GOOS == "netbsd" || (runtime.GOOS == "openbsd" && runtime.GOARCH == "mips64") {
 				_, _, err1 = RawSyscall(_SYS_DUP3, uintptr(fd[i]), uintptr(nextfd), O_CLOEXEC)
+			} else if runtime.GOOS == "dragonfly" {
+				_, _, err1 = RawSyscall(SYS_FCNTL, uintptr(fd[i]), _F_DUP2FD_CLOEXEC, uintptr(nextfd))
 			} else {
 				_, _, err1 = RawSyscall(SYS_DUP2, uintptr(fd[i]), uintptr(nextfd), 0)
 				if err1 != 0 {
diff --git a/src/syscall/syscall_dragonfly.go b/src/syscall/syscall_dragonfly.go
index 1a3cfe51fa..1a1f1f6942 100644
--- a/src/syscall/syscall_dragonfly.go
+++ b/src/syscall/syscall_dragonfly.go
@@ -22,7 +22,10 @@ func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
 func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
 func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
 
-const _SYS_DUP3 = 0
+const (
+	_SYS_DUP3         = 0
+	_F_DUP2FD_CLOEXEC = F_DUP2FD_CLOEXEC
+)
 
 // See version list in https://github.com/DragonFlyBSD/DragonFlyBSD/blob/master/sys/sys/param.h
 var (
diff --git a/src/syscall/syscall_netbsd.go b/src/syscall/syscall_netbsd.go
index d8efb41d20..7f7c5b1c6b 100644
--- a/src/syscall/syscall_netbsd.go
+++ b/src/syscall/syscall_netbsd.go
@@ -20,7 +20,10 @@ func Syscall9(num, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr,
 func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
 func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
 
-const _SYS_DUP3 = SYS_DUP3
+const (
+	_SYS_DUP3         = SYS_DUP3
+	_F_DUP2FD_CLOEXEC = 0
+)
 
 type SockaddrDatalink struct {
 	Len    uint8
diff --git a/src/syscall/syscall_openbsd_mips64.go b/src/syscall/syscall_openbsd_mips64.go
index 4508ad99b4..838c684750 100644
--- a/src/syscall/syscall_openbsd_mips64.go
+++ b/src/syscall/syscall_openbsd_mips64.go
@@ -4,7 +4,10 @@
 
 package syscall
 
-const _SYS_DUP3 = SYS_DUP3
+const (
+	_SYS_DUP3         = SYS_DUP3
+	_F_DUP2FD_CLOEXEC = 0
+)
 
 func setTimespec(sec, nsec int64) Timespec {
 	return Timespec{Sec: sec, Nsec: nsec}