diff --git a/src/lang/catalan.txt b/src/lang/catalan.txt
--- a/src/lang/catalan.txt
+++ b/src/lang/catalan.txt
@@ -941,6 +941,7 @@ STR_OPTIONS_LANG_TIP                    
 
 STR_OPTIONS_FULLSCREEN                                          :{BLACK}Pantalla Completa
 STR_OPTIONS_FULLSCREEN_TIP                                      :{BLACK}Marca la casella per tenir l'OpenTTD en pantalla completa
+STR_FULLSCREEN_FAILED                                           :{WHITE}El mode en pantalla completa ha fallat
 
 STR_OPTIONS_RES                                                 :{BLACK}Resolució de Pantalla
 STR_OPTIONS_RES_CBO                                             :{BLACK}{SKIP}{SKIP}{SKIP}{SKIP}{SKIP}{SKIP}{SKIP}{STRING}