--- a/cmake/sdlchecks.cmake
+++ b/cmake/sdlchecks.cmake
@@ -745,6 +745,7 @@
       set(SDL_VIDEO_DRIVER_DIRECTFB 1)
       set(SDL_VIDEO_RENDER_DIRECTFB 1)
       list(APPEND EXTRA_CFLAGS ${PKG_DIRECTFB_CFLAGS})
+      list(JOIN PKG_DIRECTFB_CFLAGS " " SDL_CFLAGS)
       if(SDL_DIRECTFB_SHARED AND NOT HAVE_SDL_LOADSO)
         message_warn("You must have SDL_LoadObject() support for dynamic DirectFB loading")
       endif()