fix operator=
diff --git a/xbyak/xbyak_util.h b/xbyak/xbyak_util.h
index e54f30d..ad6cdca 100644
--- a/xbyak/xbyak_util.h
+++ b/xbyak/xbyak_util.h
@@ -320,6 +320,7 @@
 	}
 	Pack& operator=(const Pack& rhs)
 	{
+		n_ = rhs.n_;
 		for (size_t i = 0; i < n_; i++) tbl_[i] = rhs.tbl_[i];
 		return *this;
 	}