Make Error: worker-http.c:496:24: fatal error: http-heads.h: No such file or directory

An error happened when I'm compiling ocserv. make throws out error: worker-http.c:496:24: fatal error: http-heads.h: No such file or directory.

ocserv version: 0.10.x

OS version: Ubuntu 14.04

Compile with: gnutls 3.3.29