error in make run/demo

Hi, I have genode 13.08 and installed genode-toolchain-11.11.tar.bz2. I have further created build.lx directory I am getting following error when I am giving make run/demo command.

Program drivers/framebuffer/sdl/fb_sdl COMPILE fb_sdl.o /home/kartikpradyumna/Downloads/genode-13.08/os/src/drivers/framebuffer/sdl/fb_sdl.cc:15:21: fatal error: SDL/SDL.h: No such file or directory compilation terminated. make[3]: *** [fb_sdl.o] Error 1 make[2]: *** [fb_sdl.prg] Error 2 make[1]: *** [gen_deps_and_build_targets] Error 2 make[1]: Leaving directory `/home/kartikpradyumna/Downloads/genode-13.08/build.lx' Error: Genode build failed make: *** [run/demo] Error 252

How to rectify this error?

Thank you. Kartik