diff --git a/src/PhpSpreadsheet/Reader/Xml.php b/src/PhpSpreadsheet/Reader/Xml.php
index f38a951562..b1df0ef5e9 100644
--- a/src/PhpSpreadsheet/Reader/Xml.php
+++ b/src/PhpSpreadsheet/Reader/Xml.php
@@ -2,6 +2,8 @@
 
 namespace PhpOffice\PhpSpreadsheet\Reader;
 
+use DateTime;
+use DateTimeZone;
 use PhpOffice\PhpSpreadsheet\Cell\AddressHelper;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Cell\DataType;
@@ -557,7 +559,8 @@ public function loadIntoExisting($pFilename, Spreadsheet $spreadsheet)
                                         break;
                                     case 'DateTime':
                                         $type = DataType::TYPE_NUMERIC;
-                                        $cellValue = Date::PHPToExcel(strtotime($cellValue . ' UTC'));
+                                        $dateTime = new DateTime($cellValue, new DateTimeZone('UTC'));
+                                        $cellValue = Date::PHPToExcel($dateTime);
 
                                         break;
                                     case 'Error':
diff --git a/src/PhpSpreadsheet/Style/NumberFormat.php b/src/PhpSpreadsheet/Style/NumberFormat.php
index a96d2ac3cb..a623657b2c 100644
--- a/src/PhpSpreadsheet/Style/NumberFormat.php
+++ b/src/PhpSpreadsheet/Style/NumberFormat.php
@@ -502,6 +502,10 @@ private static function formatAsDate(&$value, &$format): void
         $format = preg_replace_callback('/"(.*)"/U', ['self', 'escapeQuotesCallback'], $format);
 
         $dateObj = Date::excelToDateTimeObject($value);
+        // If the colon preceding minute had been quoted, as happens in
+        // Excel 2003 XML formats, m will not have been changed to i above.
+        // Change it now.
+        $format = \preg_replace('/\\\\:m/', ':i', $format);
         $value = $dateObj->format($format);
     }
 
diff --git a/tests/PhpSpreadsheetTests/Reader/Xml/XmlLoadTest.php b/tests/PhpSpreadsheetTests/Reader/Xml/XmlLoadTest.php
index 969571f2a5..3783c1a948 100644
--- a/tests/PhpSpreadsheetTests/Reader/Xml/XmlLoadTest.php
+++ b/tests/PhpSpreadsheetTests/Reader/Xml/XmlLoadTest.php
@@ -36,6 +36,10 @@ public function testLoad(): void
         self::assertEquals('# ?0/??0', $sheet->getCell('A11')->getStyle()->getNumberFormat()->getFormatCode());
         // Same pattern, same value, different display in Gnumeric vs Excel
         //self::assertEquals('1 1/2', $sheet->getCell('A11')->getFormattedValue());
+        self::assertEquals('hh":"mm":"ss', $sheet->getCell('A13')->getStyle()->getNumberFormat()->getFormatCode());
+        self::assertEquals('02:30:00', $sheet->getCell('A13')->getFormattedValue());
+        self::assertEquals('d/m/yy hh":"mm', $sheet->getCell('A15')->getStyle()->getNumberFormat()->getFormatCode());
+        self::assertEquals('19/12/60 01:30', $sheet->getCell('A15')->getFormattedValue());
 
         self::assertEquals('=B1+C1', $sheet->getCell('H1')->getValue());
         self::assertEquals('=E2&F2', $sheet->getCell('J2')->getValue());
diff --git a/tests/PhpSpreadsheetTests/Shared/DateTest.php b/tests/PhpSpreadsheetTests/Shared/DateTest.php
index 7254635ea3..550e2f6a9c 100644
--- a/tests/PhpSpreadsheetTests/Shared/DateTest.php
+++ b/tests/PhpSpreadsheetTests/Shared/DateTest.php
@@ -8,16 +8,20 @@
 
 class DateTest extends TestCase
 {
+    private $excelCalendar;
+
     private $dttimezone;
 
     protected function setUp(): void
     {
         $this->dttimezone = Date::getDefaultTimeZone();
+        $this->excelCalendar = Date::getExcelCalendar();
     }
 
     protected function tearDown(): void
     {
         Date::setDefaultTimeZone($this->dttimezone);
+        Date::setExcelCalendar($this->excelCalendar);
     }
 
     public function testSetExcelCalendar(): void
@@ -47,6 +51,9 @@ public function testSetExcelCalendarWithInvalidValue(): void
      */
     public function testDateTimeExcelToTimestamp1900($expectedResult, ...$args): void
     {
+        if (is_numeric($expectedResult) && ($expectedResult > PHP_INT_MAX || $expectedResult < PHP_INT_MIN)) {
+            self::markTestSkipped('Test invalid on 32-bit system.');
+        }
         Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
 
         $result = Date::excelToTimestamp(...$args);
@@ -119,6 +126,9 @@ public function providerDateTimeFormattedPHPToExcel1900()
      */
     public function testDateTimeExcelToTimestamp1904($expectedResult, ...$args): void
     {
+        if (is_numeric($expectedResult) && ($expectedResult > PHP_INT_MAX || $expectedResult < PHP_INT_MIN)) {
+            self::markTestSkipped('Test invalid on 32-bit system.');
+        }
         Date::setExcelCalendar(Date::CALENDAR_MAC_1904);
 
         $result = Date::excelToTimestamp(...$args);
@@ -171,6 +181,9 @@ public function providerIsDateTimeFormatCode()
      */
     public function testDateTimeExcelToTimestamp1900Timezone($expectedResult, ...$args): void
     {
+        if (is_numeric($expectedResult) && ($expectedResult > PHP_INT_MAX || $expectedResult < PHP_INT_MIN)) {
+            self::markTestSkipped('Test invalid on 32-bit system.');
+        }
         Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
 
         $result = Date::excelToTimestamp(...$args);
diff --git a/tests/data/Shared/Date/ExcelToTimestamp1900.php b/tests/data/Shared/Date/ExcelToTimestamp1900.php
index ab79731e3a..ffcd194f46 100644
--- a/tests/data/Shared/Date/ExcelToTimestamp1900.php
+++ b/tests/data/Shared/Date/ExcelToTimestamp1900.php
@@ -72,4 +72,11 @@
         10666,
         0.12345,
     ],
+    // 29-Apr-2038 00:00:00 beyond PHP 32-bit Latest Date
+    [
+        2156112000,
+        50524,
+    ],
+    [-2147483648, -2147483648 / 86400], // Okay on 64- and 32-bit systems
+    [-2147483649, -2147483649 / 86400], // Skipped test on 32-bit
 ];
diff --git a/tests/data/Shared/Date/ExcelToTimestamp1904.php b/tests/data/Shared/Date/ExcelToTimestamp1904.php
index 1c013ab4ef..fc55238af7 100644
--- a/tests/data/Shared/Date/ExcelToTimestamp1904.php
+++ b/tests/data/Shared/Date/ExcelToTimestamp1904.php
@@ -42,4 +42,9 @@
         gmmktime(13, 02, 13, 1, 1, 1904), // 32-bit safe - no Y2038 problem
         0.54321,
     ],
+    // 29-Apr-2038 00:00:00 beyond PHP 32-bit Latest Date
+    [
+        2156112000,
+        49062,
+    ],
 ];