diff --git a/libc/arch-x86/syscalls.mk b/libc/arch-x86/syscalls.mk
index dbc55e6..6a528e3 100644
--- a/libc/arch-x86/syscalls.mk
+++ b/libc/arch-x86/syscalls.mk
@@ -40,6 +40,7 @@
 syscall_src += arch-x86/syscalls/prctl.S
 syscall_src += arch-x86/syscalls/capget.S
 syscall_src += arch-x86/syscalls/capset.S
+syscall_src += arch-x86/syscalls/sigaltstack.S
 syscall_src += arch-x86/syscalls/acct.S
 syscall_src += arch-x86/syscalls/read.S
 syscall_src += arch-x86/syscalls/write.S