diff --git a/libc/arch-x86_64/syscalls/munmap.S b/libc/arch-x86_64/syscalls/munmap.S
index 4360bd0..f423a66 100644
--- a/libc/arch-x86_64/syscalls/munmap.S
+++ b/libc/arch-x86_64/syscalls/munmap.S
@@ -2,6 +2,8 @@
 
 #include <private/bionic_asm.h>
 
+    .hidden __set_errno
+
 ENTRY(munmap)
     movl    $__NR_munmap, %eax
     syscall