--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -128,6 +128,9 @@
 find_package(OpenGL REQUIRED)
 include_directories(${OPENGL_INCLUDE_DIR})
 
+find_package(X11 REQUIRED)
+include_directories(${X11_INCLUDE_DIR})
+
 if(UNIX AND NOT APPLE)
     find_library(IRRLICHT_XF86VM_LIBRARY Xxf86vm)
     mark_as_advanced(IRRLICHT_XF86VM_LIBRARY)