diff --git a/src/pkg/syscall/syscall_darwin.go b/src/pkg/syscall/syscall_darwin.go
index 1946ecd78ca11e0fe9c269e99c221489c32b1850..291ea557b0aa7a2a0a9c84092c04717aa6ffa400 100644
--- a/src/pkg/syscall/syscall_darwin.go
+++ b/src/pkg/syscall/syscall_darwin.go
@@ -552,7 +552,7 @@ func Kill(pid int, signum int) (errno int) { return kill(pid, signum, 1) }
 //sys	Symlink(path string, link string) (errno int)
 //sys	Sync() (errno int)
 //sys	Truncate(path string, length int64) (errno int)
-//sys	Umask(newmask int) (errno int)
+//sys	Umask(newmask int) (oldmask int)
 //sys	Undelete(path string) (errno int)
 //sys	Unlink(path string) (errno int)
 //sys	Unmount(path string, flags int) (errno int)
diff --git a/src/pkg/syscall/syscall_freebsd.go b/src/pkg/syscall/syscall_freebsd.go
index 906955e9794e513caba71b549095276edd4352a5..f5bb4541241713366e25519b822411dcd0073164 100644
--- a/src/pkg/syscall/syscall_freebsd.go
+++ b/src/pkg/syscall/syscall_freebsd.go
@@ -549,7 +549,7 @@ func SysctlUint32(name string) (value uint32, errno int) {
 //sys	Symlink(path string, link string) (errno int)
 //sys	Sync() (errno int)
 //sys	Truncate(path string, length int64) (errno int)
-//sys	Umask(newmask int) (errno int)
+//sys	Umask(newmask int) (oldmask int)
 //sys	Undelete(path string) (errno int)
 //sys	Unlink(path string) (errno int)
 //sys	Unmount(path string, flags int) (errno int)
diff --git a/src/pkg/syscall/zsyscall_darwin_386.go b/src/pkg/syscall/zsyscall_darwin_386.go
index 6442f078b3bd02202dbfcc210269607fb909b285..92525e3a80d79212814239f30bd25d2c2462f14b 100644
--- a/src/pkg/syscall/zsyscall_darwin_386.go
+++ b/src/pkg/syscall/zsyscall_darwin_386.go
@@ -623,9 +623,9 @@ func Truncate(path string, length int64) (errno int) {
 	return
 }
 
-func Umask(newmask int) (errno int) {
-	_, _, e1 := Syscall(SYS_UMASK, uintptr(newmask), 0, 0)
-	errno = int(e1)
+func Umask(newmask int) (oldmask int) {
+	r0, _, _ := Syscall(SYS_UMASK, uintptr(newmask), 0, 0)
+	oldmask = int(r0)
 	return
 }
 
diff --git a/src/pkg/syscall/zsyscall_darwin_amd64.go b/src/pkg/syscall/zsyscall_darwin_amd64.go
index 5f4f9ee1d2409d0ea09a046fef4fd86b5135d72c..a0fc52c85ed3e0927b00f8cb4d4e86b58a2a2277 100644
--- a/src/pkg/syscall/zsyscall_darwin_amd64.go
+++ b/src/pkg/syscall/zsyscall_darwin_amd64.go
@@ -623,9 +623,9 @@ func Truncate(path string, length int64) (errno int) {
 	return
 }
 
-func Umask(newmask int) (errno int) {
-	_, _, e1 := Syscall(SYS_UMASK, uintptr(newmask), 0, 0)
-	errno = int(e1)
+func Umask(newmask int) (oldmask int) {
+	r0, _, _ := Syscall(SYS_UMASK, uintptr(newmask), 0, 0)
+	oldmask = int(r0)
 	return
 }
 
diff --git a/src/pkg/syscall/zsyscall_freebsd_386.go b/src/pkg/syscall/zsyscall_freebsd_386.go
index 9e165086a450b7bbacb22546a213620a626da361..9e22134180cf898d16a77f6728f39afc6d51515c 100644
--- a/src/pkg/syscall/zsyscall_freebsd_386.go
+++ b/src/pkg/syscall/zsyscall_freebsd_386.go
@@ -623,9 +623,9 @@ func Truncate(path string, length int64) (errno int) {
 	return
 }
 
-func Umask(newmask int) (errno int) {
-	_, _, e1 := Syscall(SYS_UMASK, uintptr(newmask), 0, 0)
-	errno = int(e1)
+func Umask(newmask int) (oldmask int) {
+	r0, _, _ := Syscall(SYS_UMASK, uintptr(newmask), 0, 0)
+	oldmask = int(r0)
 	return
 }
 
diff --git a/src/pkg/syscall/zsyscall_freebsd_amd64.go b/src/pkg/syscall/zsyscall_freebsd_amd64.go
index f6d42bcd341a68e32d1badc00ce35838261d07e6..da67cdb829c2126fc5de6ae6f0293c0ae052a0a8 100644
--- a/src/pkg/syscall/zsyscall_freebsd_amd64.go
+++ b/src/pkg/syscall/zsyscall_freebsd_amd64.go
@@ -623,9 +623,9 @@ func Truncate(path string, length int64) (errno int) {
 	return
 }
 
-func Umask(newmask int) (errno int) {
-	_, _, e1 := Syscall(SYS_UMASK, uintptr(newmask), 0, 0)
-	errno = int(e1)
+func Umask(newmask int) (oldmask int) {
+	r0, _, _ := Syscall(SYS_UMASK, uintptr(newmask), 0, 0)
+	oldmask = int(r0)
 	return
 }