diff --git a/ui/sdl2.c b/ui/sdl2.c
index 189d26e2a9..a578017268 100644
--- a/ui/sdl2.c
+++ b/ui/sdl2.c
@@ -275,6 +275,8 @@ static void sdl_send_mouse_event(struct sdl2_console *scon, int dx, int dy,
         [INPUT_BUTTON_LEFT]       = SDL_BUTTON(SDL_BUTTON_LEFT),
         [INPUT_BUTTON_MIDDLE]     = SDL_BUTTON(SDL_BUTTON_MIDDLE),
         [INPUT_BUTTON_RIGHT]      = SDL_BUTTON(SDL_BUTTON_RIGHT),
+        [INPUT_BUTTON_SIDE]       = SDL_BUTTON(SDL_BUTTON_X1),
+        [INPUT_BUTTON_EXTRA]      = SDL_BUTTON(SDL_BUTTON_X2)
     };
     static uint32_t prev_state;