--- widelands-build21/xdg/CMakeLists.txt.orig	2020-07-12 21:33:44.000000000 +0200
+++ widelands-build21/xdg/CMakeLists.txt	2020-07-29 06:20:12.689266184 +0200
@@ -6,19 +6,19 @@
 list(APPEND icon_sizes "16" "32" "48" "64" "128")
 foreach (icon_size ${icon_sizes})
   #install(FILES ${CMAKE_SOURCE_DIR}/data/images/logos/wl-ico-${icon_size}.png DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/icons/hicolor/${icon_size}x${icon_size}/apps RENAME ${XDG_APPLICATION_ID}.png)
-  install(FILES ${CMAKE_SOURCE_DIR}/data/images/logos/wl-ico-${icon_size}.png DESTINATION ../share/icons/hicolor/${icon_size}x${icon_size}/apps RENAME ${XDG_APPLICATION_ID}.png)
+  install(FILES ${CMAKE_SOURCE_DIR}/data/images/logos/wl-ico-${icon_size}.png DESTINATION ${CMAKE_INSTALL_DATADIR}/icons/hicolor/${icon_size}x${icon_size}/apps RENAME ${XDG_APPLICATION_ID}.png)
 endforeach (icon_size ${icon_sizes})
 #install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${CMAKE_PROJECT_NAME}.6           DESTINATION ${CMAKE_INSTALL_MANDIR}/man6)
-install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${CMAKE_PROJECT_NAME}.6           DESTINATION ../share/man/man6)
+install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${CMAKE_PROJECT_NAME}.6           DESTINATION ${CMAKE_INSTALL_DATADIR}/man/man6)
 #install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${XDG_APPLICATION_ID}.desktop     DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/applications)
-install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${XDG_APPLICATION_ID}.desktop     DESTINATION ../share/applications)
+install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${XDG_APPLICATION_ID}.desktop     DESTINATION ${CMAKE_INSTALL_DATADIR}/applications)
 #install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${XDG_APPLICATION_ID}.appdata.xml DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/metainfo)
-install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${XDG_APPLICATION_ID}.appdata.xml DESTINATION ../share/metainfo)
+install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${XDG_APPLICATION_ID}.appdata.xml DESTINATION ${CMAKE_INSTALL_DATADIR}/metainfo)
 
 find_program(GTK_UPDATE_ICON_CACHE NAMES gtk-update-icon-cache)
 if (GTK_UPDATE_ICON_CACHE)
   #install(CODE "execute_process (COMMAND ${GTK_UPDATE_ICON_CACHE} -t -f ${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_DATAROOTDIR}/icons/hicolor ||: )")
-  install(CODE "execute_process (COMMAND ${GTK_UPDATE_ICON_CACHE} -t -f ${CMAKE_INSTALL_PREFIX}/../share/icons/hicolor ||: )")
+  install(CODE "execute_process (COMMAND ${GTK_UPDATE_ICON_CACHE} -t -f ${CMAKE_INSTALL_DATADIR}/icons/hicolor ||: )")
 else (GTK_UPDATE_ICON_CACHE)
   message(WARNING "gtk-update-icon-cache not found!")
 endif (GTK_UPDATE_ICON_CACHE)