diff --git a/libc/arch-arm/syscalls/umount2.S b/libc/arch-arm/syscalls/umount2.S
index 4c0ce4d..841eb97 100644
--- a/libc/arch-arm/syscalls/umount2.S
+++ b/libc/arch-arm/syscalls/umount2.S
@@ -2,6 +2,8 @@
 
 #include <private/bionic_asm.h>
 
+    .hidden __set_errno
+
 ENTRY(umount2)
     mov     ip, r7
     ldr     r7, =__NR_umount2