HTTP/2 is quickly replacing HTTP/1.1, the protocol that supports the WWW for the past 17 years. However, HTTP/2’s connection management and multiplexing schemes often incur unexpected cross-layer interactions. In this paper, we propose SMig, an HTTP/2 extension that allows a client or server to migrate an on-going HTTP/2 stream from one connection to another. We demonstrate through real implementation that SMig can bring substantial performance improvement under certain common usage scenarios (e.g., up to 99% of download time reduction for small delay-sensitive objects when a concurrent large download is present).