Doh

src/asm_writing/rewriter.cpp

@@ -551,8 +551,7 @@ void Rewriter::_decref(RewriterVar* var) {
     assembler->decq(assembler::Indirect(reg, offsetof(Box, ob_refcnt)));
     {
         assembler::ForwardJump jnz(*assembler, assembler::COND_NOT_ZERO);
-        //assembler->trap();
-        assembler->mov(assembler::Indirect(reg, offsetof(Box, cls)), assembler::RAX);
+        assembler->movq(assembler::Indirect(reg, offsetof(Box, cls)), assembler::RAX);
         assembler->callq(assembler::Indirect(assembler::RAX, offsetof(BoxedClass, tp_dealloc)));
         //assembler->mov(assembler::Indirect(assembler::RAX, offsetof(BoxedClass, tp_dealloc)), assembler::R11);
         //assembler->callq(assembler::R11);