diff --git a/client.go b/client.go
index 5f457221..9423b4dd 100644
--- a/client.go
+++ b/client.go
@@ -2113,13 +2113,12 @@ func normaliseError(err error) error {
 // Unsupported flags are ignored.
 func toPflags(f int) uint32 {
 	var out uint32
-	switch f & os.O_WRONLY {
-	case os.O_WRONLY:
-		out |= sshFxfWrite
+	switch f & (os.O_RDONLY | os.O_WRONLY | os.O_RDWR) {
 	case os.O_RDONLY:
 		out |= sshFxfRead
-	}
-	if f&os.O_RDWR == os.O_RDWR {
+	case os.O_WRONLY:
+		out |= sshFxfWrite
+	case os.O_RDWR:
 		out |= sshFxfRead | sshFxfWrite
 	}
 	if f&os.O_APPEND == os.O_APPEND {
diff --git a/ls_formatting_test.go b/ls_formatting_test.go
index 8d0fefbc..d6e5e036 100644
--- a/ls_formatting_test.go
+++ b/ls_formatting_test.go
@@ -3,6 +3,7 @@ package sftp
 import (
 	"os"
 	"regexp"
+	"runtime"
 	"strings"
 	"testing"
 	"time"
@@ -101,6 +102,12 @@ func runLsTestHelper(t *testing.T, result, expectedType, path string) {
 	dateTime := strings.Join(fields[5:8], " ")
 	filename := fields[8]
 
+	if runtime.GOOS == "zos" {
+		// User and Group are always only uppercase characters on z/OS
+		user = strings.ToLower(user)
+		group = strings.ToLower(group)
+	}
+
 	// permissions (len 10, "drwxr-xr-x")
 	const (
 		rwxs = "[-r][-w][-xsS]"
diff --git a/request-server_test.go b/request-server_test.go
index 6825bf43..668d803a 100644
--- a/request-server_test.go
+++ b/request-server_test.go
@@ -780,8 +780,13 @@ func TestRequestReaddir(t *testing.T) {
 		}
 	}
 	_, err := p.cli.ReadDir("/foo_01")
-	assert.Equal(t, &StatusError{Code: sshFxFailure,
-		msg: " /foo_01: not a directory"}, err)
+	if runtime.GOOS == "zos" {
+		assert.Equal(t, &StatusError{Code: sshFxFailure,
+			msg: " /foo_01: EDC5135I Not a directory."}, err)
+	} else {
+		assert.Equal(t, &StatusError{Code: sshFxFailure,
+			msg: " /foo_01: not a directory"}, err)
+	}
 	_, err = p.cli.ReadDir("/does_not_exist")
 	assert.Equal(t, os.ErrNotExist, err)
 	di, err := p.cli.ReadDir("/")
diff --git a/server_test.go b/server_test.go
index 4cec3123..5bac81eb 100644
--- a/server_test.go
+++ b/server_test.go
@@ -99,9 +99,14 @@ func TestInvalidExtendedPacket(t *testing.T) {
 // test that server handles concurrent requests correctly
 func TestConcurrentRequests(t *testing.T) {
 	skipIfWindows(t)
-	filename := "/etc/passwd"
-	if runtime.GOOS == "plan9" {
+	var filename string
+	switch runtime.GOOS {
+	case "plan9":
 		filename = "/lib/ndb/local"
+	case "zos":
+		filename = "/etc/.shrc"
+	default:
+		filename = "/etc/passwd"
 	}
 	client, server := clientServerPair(t)
 	defer client.Close()
diff --git a/stat_posix.go b/stat_posix.go
index 5b870e23..a15b9c3b 100644
--- a/stat_posix.go
+++ b/stat_posix.go
@@ -1,5 +1,6 @@
-//go:build !plan9
+//go:build !plan9 && !zos
 // +build !plan9
+// +build !zos
 
 package sftp
 
diff --git a/stat_zos.go b/stat_zos.go
new file mode 100644
index 00000000..3643e5ea
--- /dev/null
+++ b/stat_zos.go
@@ -0,0 +1,137 @@
+//go:build zos
+// +build zos
+
+package sftp
+
+import (
+	"os"
+	"syscall"
+)
+
+const EBADF = syscall.EBADF
+
+// z/OS syscall constants are not compatible with the stat structure returned
+// from the server. Define the OpenBSD ones here instead.
+const (
+	S_IFMT   = 0xF000
+	S_IFIFO  = 0x1000
+	S_IFCHR  = 0x2000
+	S_IFDIR  = 0x4000
+	S_IFBLK  = 0x6000
+	S_IFREG  = 0x8000
+	S_IFLNK  = 0xA000
+	S_IFSOCK = 0xC000
+)
+
+func wrapPathError(filepath string, err error) error {
+	if errno, ok := err.(syscall.Errno); ok {
+		return &os.PathError{Path: filepath, Err: errno}
+	}
+	return err
+}
+
+// translateErrno translates a syscall error number to a SFTP error code.
+func translateErrno(errno syscall.Errno) uint32 {
+	switch errno {
+	case 0:
+		return sshFxOk
+	case syscall.ENOENT:
+		return sshFxNoSuchFile
+	case syscall.EACCES, syscall.EPERM:
+		return sshFxPermissionDenied
+	}
+
+	return sshFxFailure
+}
+
+func translateSyscallError(err error) (uint32, bool) {
+	switch e := err.(type) {
+	case syscall.Errno:
+		return translateErrno(e), true
+	case *os.PathError:
+		debug("statusFromError,pathError: error is %T %#v", e.Err, e.Err)
+		if errno, ok := e.Err.(syscall.Errno); ok {
+			return translateErrno(errno), true
+		}
+	}
+	return 0, false
+}
+
+// isRegular returns true if the mode describes a regular file.
+func isRegular(mode uint32) bool {
+	return mode&S_IFMT == S_IFREG
+}
+
+// toFileMode converts sftp filemode bits to the os.FileMode specification
+func toFileMode(mode uint32) os.FileMode {
+	var fm = os.FileMode(mode & 0777)
+
+	switch mode & S_IFMT {
+	case S_IFBLK:
+		fm |= os.ModeDevice
+	case S_IFCHR:
+		fm |= os.ModeDevice | os.ModeCharDevice
+	case S_IFDIR:
+		fm |= os.ModeDir
+	case S_IFIFO:
+		fm |= os.ModeNamedPipe
+	case S_IFLNK:
+		fm |= os.ModeSymlink
+	case S_IFREG:
+		// nothing to do
+	case S_IFSOCK:
+		fm |= os.ModeSocket
+	}
+
+	if mode&syscall.S_ISUID != 0 {
+		fm |= os.ModeSetuid
+	}
+	if mode&syscall.S_ISGID != 0 {
+		fm |= os.ModeSetgid
+	}
+	if mode&syscall.S_ISVTX != 0 {
+		fm |= os.ModeSticky
+	}
+
+	return fm
+}
+
+// fromFileMode converts from the os.FileMode specification to sftp filemode bits
+func fromFileMode(mode os.FileMode) uint32 {
+	ret := uint32(mode & os.ModePerm)
+
+	switch mode & os.ModeType {
+	case os.ModeDevice | os.ModeCharDevice:
+		ret |= S_IFCHR
+	case os.ModeDevice:
+		ret |= S_IFBLK
+	case os.ModeDir:
+		ret |= S_IFDIR
+	case os.ModeNamedPipe:
+		ret |= S_IFIFO
+	case os.ModeSymlink:
+		ret |= S_IFLNK
+	case 0:
+		ret |= S_IFREG
+	case os.ModeSocket:
+		ret |= S_IFSOCK
+	}
+
+	if mode&os.ModeSetuid != 0 {
+		ret |= syscall.S_ISUID
+	}
+	if mode&os.ModeSetgid != 0 {
+		ret |= syscall.S_ISGID
+	}
+	if mode&os.ModeSticky != 0 {
+		ret |= syscall.S_ISVTX
+	}
+
+	return ret
+}
+
+const (
+	s_ISUID = syscall.S_ISUID
+	s_ISGID = syscall.S_ISGID
+	s_ISVTX = syscall.S_ISVTX
+)
diff --git a/syscall_good.go b/syscall_good.go
index 50052189..235d6039 100644
--- a/syscall_good.go
+++ b/syscall_good.go
@@ -1,6 +1,7 @@
-//go:build !plan9 && !windows && (!js || !wasm)
+//go:build !plan9 && !windows && !zos && (!js || !wasm)
 // +build !plan9
 // +build !windows
+// +build !zos
 // +build !js !wasm
 
 package sftp