Currently, the Intellectual Properties (IP) and their reuse are common, however the use of IP is raising design security issues i.e. counterfeiter, reverse engineering. Watermarking is one of the efficient methods to detect an unauthorized IP use and a counterfeiter. In this context, many interesting works have been proposed. However, a few of them combine the watermarking process with the synthesis one. This article presents a new automatic and low cost watermarking solution. The design watermark is implanted in a high-level synthesis process. Some implementation results with Xilinx Virtex-5 FPGA assure the proposed solution low overhead compared toexisting solution.