diff --git a/encode_vm.go b/encode_vm.go
index bd732cc..2bb7349 100644
--- a/encode_vm.go
+++ b/encode_vm.go
@@ -654,7 +654,7 @@ func (e *Encoder) run(ctx *encodeRuntimeContext, code *opcode) error {
 			}
 			ctxptr = ctx.ptr() + ptrOffset // assign new ctxptr
 
-			store(ctxptr, 0, ptr)
+			store(ctxptr, c.idx, ptr)
 			store(ctxptr, lastCode.idx, oldOffset)
 			store(ctxptr, lastCode.elemIdx, uintptr(unsafe.Pointer(code.next)))