--- /dev/null
+--TEST--
+Bug #45529 (UTC not properly recognised as timezone identifier while parsing)
+--FILE--
+<?php
+$tz1 = new DateTimeZone('UTC');
+$tz2 = date_create('UTC')->getTimeZone();
+echo $tz1->getName(), PHP_EOL;
+echo $tz2->getName(), PHP_EOL;
+$d = new DateTime('2008-01-01 12:00:00+0200');
+$d->setTimeZone($tz1);
+echo $d->format(DATE_ISO8601), PHP_EOL;
+$d = new DateTime('2008-01-01 12:00:00+0200');
+$d->setTimeZone($tz2);
+echo $d->format(DATE_ISO8601), PHP_EOL;
+?>
+--EXPECT--
+UTC
+UTC
+2008-01-01T10:00:00+0000
+2008-01-01T10:00:00+0000