add sigaltstack syscall
diff --git a/libc/include/sys/linux-syscalls.h b/libc/include/sys/linux-syscalls.h
index c4e6e45..30c58fd 100644
--- a/libc/include/sys/linux-syscalls.h
+++ b/libc/include/sys/linux-syscalls.h
@@ -42,6 +42,7 @@
#define __NR_prctl (__NR_SYSCALL_BASE + 172)
#define __NR_capget (__NR_SYSCALL_BASE + 184)
#define __NR_capset (__NR_SYSCALL_BASE + 185)
+#define __NR_sigaltstack (__NR_SYSCALL_BASE + 186)
#define __NR_acct (__NR_SYSCALL_BASE + 51)
#define __NR_read (__NR_SYSCALL_BASE + 3)
#define __NR_write (__NR_SYSCALL_BASE + 4)