diff --git a/src/lang/unfinished/frisian.txt b/src/lang/unfinished/frisian.txt
--- a/src/lang/unfinished/frisian.txt
+++ b/src/lang/unfinished/frisian.txt
@@ -1687,18 +1687,9 @@ STR_INTRO_TOOLTIP_QUIT                                          :{BLACK}Slút 'OpenTTD' ôf
 
 # Quit window
 STR_QUIT_CAPTION                                                :{WHITE}Ôfslúte
-STR_QUIT_ARE_YOU_SURE_YOU_WANT_TO_EXIT_OPENTTD                  :{YELLOW}Witte jo seker dat jo dit spul ôfslúte wolle en werom gean wolle nei {STRING}?
 STR_QUIT_YES                                                    :{BLACK}Ja
 STR_QUIT_NO                                                     :{BLACK}Nee
 
-# Supported OSes
-STR_OSNAME_WINDOWS                                              :Windows
-STR_OSNAME_UNIX                                                 :Unix
-STR_OSNAME_OSX                                                  :OS{NBSP}X
-STR_OSNAME_HAIKU                                                :Haiku
-STR_OSNAME_OS2                                                  :OS/2
-STR_OSNAME_SUNOS                                                :SunOS
-
 # Abandon game
 STR_ABANDON_GAME_CAPTION                                        :{WHITE}Ferlit Spul
 STR_ABANDON_GAME_QUERY                                          :{YELLOW}Wolsto echt dit lânskip slúte?