diff --git a/libc/arch-x86_64/syscalls/mlock.S b/libc/arch-x86_64/syscalls/mlock.S
index 0c69eb7..78389e2 100644
--- a/libc/arch-x86_64/syscalls/mlock.S
+++ b/libc/arch-x86_64/syscalls/mlock.S
@@ -2,6 +2,8 @@
 
 #include <private/bionic_asm.h>
 
+    .hidden __set_errno
+
 ENTRY(mlock)
     movl    $__NR_mlock, %eax
     syscall