diff --git a/libc/arch-arm/syscalls.mk b/libc/arch-arm/syscalls.mk
index 96471bf..3020930 100644
--- a/libc/arch-arm/syscalls.mk
+++ b/libc/arch-arm/syscalls.mk
@@ -37,6 +37,7 @@
 syscall_src += arch-arm/syscalls/prctl.S
 syscall_src += arch-arm/syscalls/capget.S
 syscall_src += arch-arm/syscalls/capset.S
+syscall_src += arch-arm/syscalls/sigaltstack.S
 syscall_src += arch-arm/syscalls/acct.S
 syscall_src += arch-arm/syscalls/read.S
 syscall_src += arch-arm/syscalls/write.S