diff --git a/src/video/x11/SDL_x11keyboard.c b/src/video/x11/SDL_x11keyboard.c
index 2c3acdadd..e16d9f178 100644
--- a/src/video/x11/SDL_x11keyboard.c
+++ b/src/video/x11/SDL_x11keyboard.c
@@ -129,6 +129,7 @@ static const struct {
     { XK_Control_R, SDL_SCANCODE_RCTRL },
     { XK_Shift_R, SDL_SCANCODE_RSHIFT },
     { XK_Alt_R, SDL_SCANCODE_RALT },
+    { XK_ISO_Level3_Shift, SDL_SCANCODE_RALT },
     { XK_Meta_R, SDL_SCANCODE_RGUI },
     { XK_Super_R, SDL_SCANCODE_RGUI },
     { XK_Mode_switch, SDL_SCANCODE_MODE },