diff --git a/src/net/fcntl_libc_test.go b/src/net/fcntl_libc_test.go
new file mode 100644
index 00000000000..0320d63a863
--- /dev/null
+++ b/src/net/fcntl_libc_test.go
@@ -0,0 +1,14 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build aix || darwin || solaris
+// +build aix darwin solaris
+
+package net
+
+import _ "unsafe" // for go:linkname
+
+// Implemented in the syscall package.
+//go:linkname fcntl syscall.fcntl
+func fcntl(fd int, cmd int, arg int) (int, error)
diff --git a/src/net/fcntl_syscall_test.go b/src/net/fcntl_syscall_test.go
new file mode 100644
index 00000000000..0f04bb4ed65
--- /dev/null
+++ b/src/net/fcntl_syscall_test.go
@@ -0,0 +1,21 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build dragonfly || freebsd || linux || netbsd || openbsd
+// +build dragonfly freebsd linux netbsd openbsd
+
+package net
+
+import (
+	"internal/syscall/unix"
+	"syscall"
+)
+
+func fcntl(fd int, cmd int, arg int) (int, error) {
+	r, _, e := syscall.Syscall(unix.FcntlSyscall, uintptr(fd), uintptr(cmd), uintptr(arg))
+	if e != 0 {
+		return int(r), syscall.Errno(e)
+	}
+	return int(r), nil
+}
diff --git a/src/net/unixsock_readmsg_test.go b/src/net/unixsock_readmsg_test.go
index 4961ecbe10a..a4d2fca69ce 100644
--- a/src/net/unixsock_readmsg_test.go
+++ b/src/net/unixsock_readmsg_test.go
@@ -82,22 +82,22 @@ func TestUnixConnReadMsgUnixSCMRightsCloseOnExec(t *testing.T) {
 		t.Fatalf("got scms = %#v; expected 1 SocketControlMessage", scms)
 	}
 	scm := scms[0]
-	gotFds, err := syscall.ParseUnixRights(&scm)
+	gotFDs, err := syscall.ParseUnixRights(&scm)
 	if err != nil {
 		t.Fatalf("syscall.ParseUnixRights: %v", err)
 	}
-	if len(gotFds) != 1 {
-		t.Fatalf("got FDs %#v: wanted only 1 fd", gotFds)
+	if len(gotFDs) != 1 {
+		t.Fatalf("got FDs %#v: wanted only 1 fd", gotFDs)
 	}
 	defer func() {
-		if err := syscall.Close(int(gotFds[0])); err != nil {
-			t.Fatalf("fail to close gotFds: %v", err)
+		if err := syscall.Close(gotFDs[0]); err != nil {
+			t.Fatalf("fail to close gotFDs: %v", err)
 		}
 	}()
 
-	flags, _, errno := syscall.Syscall(syscall.SYS_FCNTL, uintptr(gotFds[0]), uintptr(syscall.F_GETFD), 0)
-	if errno != 0 {
-		t.Fatalf("Can't get flags of fd:%#v, with err:%v", gotFds[0], errno)
+	flags, err := fcntl(gotFDs[0], syscall.F_GETFD, 0)
+	if err != nil {
+		t.Fatalf("Can't get flags of fd:%#v, with err:%v", gotFDs[0], err)
 	}
 	if flags&syscall.FD_CLOEXEC == 0 {
 		t.Fatalf("got flags %#x, want %#x (FD_CLOEXEC) set", flags, syscall.FD_CLOEXEC)