--- a/crawl-ref/source/ui.orig.cc	2020-03-22 05:52:08.000000000 +0100
+++ b/crawl-ref/source/ui.cc	2020-04-22 14:56:57.938271318 +0200
@@ -30,6 +30,8 @@
 # include "view.h"
 #endif
 
+#include <cwctype>
+
 #ifdef USE_TILE_WEB
 # include <unordered_map>
 #endif