diff --git a/libc/arch-arm/syscalls/truncate.S b/libc/arch-arm/syscalls/truncate.S
index bb33beb..0bee4d2 100644
--- a/libc/arch-arm/syscalls/truncate.S
+++ b/libc/arch-arm/syscalls/truncate.S
@@ -4,9 +4,11 @@
 
 ENTRY(truncate)
     mov     ip, r7
+    .cfi_register r7, ip
     ldr     r7, =__NR_truncate
     swi     #0
     mov     r7, ip
+    .cfi_restore r7
     cmn     r0, #(MAX_ERRNO + 1)
     bxls    lr
     neg     r0, r0