--- a/src/newgrf.cpp	Wed Sep 19 18:39:14 2007 +0000
+++ b/src/newgrf.cpp	Wed Sep 19 18:55:26 2007 +0000
@@ -272,6 +272,8 @@
 	TEXID_TO_STRINGID(0x482A, 0x483B, STR_482A_PRODUCTION_LAST_MONTH);
 #undef TEXTID_TO_STRINGID
 
+	if (str == STR_NULL) return STR_EMPTY;
+
 	return str;
 }