Submitted upstream at https://github.com/Swordfish90/cool-retro-term/issues/692

--- a/qmltermwidget/lib/TerminalCharacterDecoder.cpp	1969-12-31 18:00:01.000000000 -0600
+++ b/qmltermwidget/lib/TerminalCharacterDecoder.cpp	2021-12-27 22:07:04.452256118 -0600
@@ -19,6 +19,8 @@
     02110-1301  USA.
 */
 
+#include <cwctype>
+
 // Own
 #include "TerminalCharacterDecoder.h"
 
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22-02-14</span></td><td><a href='/guix/commit/tests/git.scm?id=87d49346f3072f7b4343b6fb387ee5f9311493b7'>git: Add 'commit-descendant?'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-09-18 19:37:45 +0200'>2021-09-18</span></td><td><a href='/guix/commit/tests/git.scm?id=59ee10754eddddb99e4a80b9e18aa12ed1b3d77a'>import: Add 'generic-git' updater.</a><span class='msg-avail'>...</span></td><td>Xinglu Chen</td></tr>
<tr><td><span title='2020-06-09 00:34:52 +0200'>2020-06-09</span></td><td><a href='/guix/commit/tests/git.scm?id=72357e2170e88f73c11ff089f87a744cee8606ec'>git: 'commit-difference' really excludes the ancestors of #:excluded.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
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