--- a/cmake/sdlchecks.cmake
+++ b/cmake/sdlchecks.cmake
@@ -692,6 +692,7 @@ macro(CheckDirectFB)
       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(DIRECTFB_SHARED)
         if(NOT HAVE_DLOPEN)
           message_warn("You must have SDL_LoadObject() support for dynamic DirectFB loading")
