diff --git a/libc/arch-x86_64/syscalls/sigaltstack.S b/libc/arch-x86_64/syscalls/sigaltstack.S
index 271fafc..2dd6aa4 100644
--- a/libc/arch-x86_64/syscalls/sigaltstack.S
+++ b/libc/arch-x86_64/syscalls/sigaltstack.S
@@ -2,6 +2,8 @@
 
 #include <private/bionic_asm.h>
 
+    .hidden __set_errno
+
 ENTRY(sigaltstack)
     movl    $__NR_sigaltstack, %eax
     syscall