diff --git a/unix/syscall_linux.go b/unix/syscall_linux.go
index 47146911f..583ff00d5 100644
--- a/unix/syscall_linux.go
+++ b/unix/syscall_linux.go
@@ -2368,6 +2368,16 @@ func Setitimer(which ItimerWhich, it Itimerval) (Itimerval, error) {
 	return prev, nil
 }
 
+//sysnb	rtSigprocmask(how int, set *Sigset_t, oldset *Sigset_t, sigsetsize uintptr) (err error) = SYS_RT_SIGPROCMASK
+
+func PthreadSigmask(how int, set, oldset *Sigset_t) error {
+	if oldset != nil {
+		// Explicitly clear in case Sigset_t is larger than _C__NSIG.
+		*oldset = Sigset_t{}
+	}
+	return rtSigprocmask(how, set, oldset, _C__NSIG/8)
+}
+
 /*
  * Unimplemented
  */
@@ -2426,7 +2436,6 @@ func Setitimer(which ItimerWhich, it Itimerval) (Itimerval, error) {
 // RestartSyscall
 // RtSigaction
 // RtSigpending
-// RtSigprocmask
 // RtSigqueueinfo
 // RtSigreturn
 // RtSigsuspend
diff --git a/unix/zsyscall_linux.go b/unix/zsyscall_linux.go
index bc4a27531..293cf3680 100644
--- a/unix/zsyscall_linux.go
+++ b/unix/zsyscall_linux.go
@@ -2151,3 +2151,13 @@ func setitimer(which int, newValue *Itimerval, oldValue *Itimerval) (err error)
 	}
 	return
 }
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func rtSigprocmask(how int, set *Sigset_t, oldset *Sigset_t, sigsetsize uintptr) (err error) {
+	_, _, e1 := RawSyscall6(SYS_RT_SIGPROCMASK, uintptr(how), uintptr(unsafe.Pointer(set)), uintptr(unsafe.Pointer(oldset)), uintptr(sigsetsize), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}