diff --git a/tests/PhpSpreadsheetTests/Reader/Ods/HiddenMergeCellsTest.php b/tests/PhpSpreadsheetTests/Reader/Ods/HiddenMergeCellsTest.php
new file mode 100644
index 00000000..710b292a
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Reader/Ods/HiddenMergeCellsTest.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Ods;
+
+use PhpOffice\PhpSpreadsheet\Reader\Ods;
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PHPUnit\Framework\TestCase;
+
+class HiddenMergeCellsTest extends TestCase
+{
+    /**
+     * @var Spreadsheet
+     */
+    private $spreadsheet;
+
+    protected function setup(): void
+    {
+        $filename = 'tests/data/Reader/Ods/HiddenMergeCellsTest.ods';
+        $reader = new Ods();
+        $this->spreadsheet = $reader->load($filename);
+    }
+
+    public function testHiddenMergeCells(): void
+    {
+        $c2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('C2')->isInMergeRange();
+        self::assertTrue($c2InMergeRange);
+        $a2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('A2')->isInMergeRange();
+        self::assertTrue($a2InMergeRange);
+        $a2MergeRangeValue = $this->spreadsheet->getActiveSheet()->getCell('A2')->isMergeRangeValueCell();
+        self::assertTrue($a2MergeRangeValue);
+
+        $cellArray = $this->spreadsheet->getActiveSheet()->rangeToArray('A2:C2');
+        self::assertSame([[12, 4, 3]], $cellArray);
+    }
+
+    public function testUnmergeHiddenMergeCells(): void
+    {
+        $this->spreadsheet->getActiveSheet()->unmergeCells('A2:C2');
+
+        $c2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('C2')->isInMergeRange();
+        self::assertFalse($c2InMergeRange);
+        $a2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('A2')->isInMergeRange();
+        self::assertFalse($a2InMergeRange);
+
+        $cellArray = $this->spreadsheet->getActiveSheet()->rangeToArray('A2:C2', null, false, false, false);
+        self::assertSame([[12, '=6-B1', '=A2/B2']], $cellArray);
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Reader/Xls/HiddenMergeCellsTest.php b/tests/PhpSpreadsheetTests/Reader/Xls/HiddenMergeCellsTest.php
new file mode 100644
index 00000000..c7085281
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Reader/Xls/HiddenMergeCellsTest.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xls;
+
+use PhpOffice\PhpSpreadsheet\Reader\Xls;
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PHPUnit\Framework\TestCase;
+
+class HiddenMergeCellsTest extends TestCase
+{
+    /**
+     * @var Spreadsheet
+     */
+    private $spreadsheet;
+
+    protected function setup(): void
+    {
+        $filename = 'tests/data/Reader/XLS/HiddenMergeCellsTest.xls';
+        $reader = new Xls();
+        $this->spreadsheet = $reader->load($filename);
+    }
+
+    public function testHiddenMergeCells(): void
+    {
+        $c2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('C2')->isInMergeRange();
+        self::assertTrue($c2InMergeRange);
+        $a2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('A2')->isInMergeRange();
+        self::assertTrue($a2InMergeRange);
+        $a2MergeRangeValue = $this->spreadsheet->getActiveSheet()->getCell('A2')->isMergeRangeValueCell();
+        self::assertTrue($a2MergeRangeValue);
+
+        $cellArray = $this->spreadsheet->getActiveSheet()->rangeToArray('A2:C2');
+        self::assertSame([[12, 4, 3]], $cellArray);
+    }
+
+    public function testUnmergeHiddenMergeCells(): void
+    {
+        $this->spreadsheet->getActiveSheet()->unmergeCells('A2:C2');
+
+        $c2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('C2')->isInMergeRange();
+        self::assertFalse($c2InMergeRange);
+        $a2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('A2')->isInMergeRange();
+        self::assertFalse($a2InMergeRange);
+
+        $cellArray = $this->spreadsheet->getActiveSheet()->rangeToArray('A2:C2', null, false, false, false);
+        self::assertSame([[12, '=6-B1', '=A2/B2']], $cellArray);
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Reader/Xlsx/HiddenMergeCellsTest.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/HiddenMergeCellsTest.php
new file mode 100644
index 00000000..4919cd27
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/HiddenMergeCellsTest.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
+
+use PhpOffice\PhpSpreadsheet\Reader\Xlsx;
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PHPUnit\Framework\TestCase;
+
+class HiddenMergeCellsTest extends TestCase
+{
+    /**
+     * @var Spreadsheet
+     */
+    private $spreadsheet;
+
+    protected function setup(): void
+    {
+        $filename = 'tests/data/Reader/XLSX/HiddenMergeCellsTest.xlsx';
+        $reader = new Xlsx();
+        $this->spreadsheet = $reader->load($filename);
+    }
+
+    public function testHiddenMergeCells(): void
+    {
+        $c2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('C2')->isInMergeRange();
+        self::assertTrue($c2InMergeRange);
+        $a2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('A2')->isInMergeRange();
+        self::assertTrue($a2InMergeRange);
+        $a2MergeRangeValue = $this->spreadsheet->getActiveSheet()->getCell('A2')->isMergeRangeValueCell();
+        self::assertTrue($a2MergeRangeValue);
+
+        $cellArray = $this->spreadsheet->getActiveSheet()->rangeToArray('A2:C2');
+        self::assertSame([[12, 4, 3]], $cellArray);
+    }
+
+    public function testUnmergeHiddenMergeCells(): void
+    {
+        $this->spreadsheet->getActiveSheet()->unmergeCells('A2:C2');
+
+        $c2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('C2')->isInMergeRange();
+        self::assertFalse($c2InMergeRange);
+        $a2InMergeRange = $this->spreadsheet->getActiveSheet()->getCell('A2')->isInMergeRange();
+        self::assertFalse($a2InMergeRange);
+
+        $cellArray = $this->spreadsheet->getActiveSheet()->rangeToArray('A2:C2', null, false, false, false);
+        self::assertSame([[12, '=6-B1', '=A2/B2']], $cellArray);
+    }
+}
diff --git a/tests/data/Reader/Ods/HiddenMergeCellsTest.ods b/tests/data/Reader/Ods/HiddenMergeCellsTest.ods
new file mode 100644
index 00000000..b8beb972
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diff --git a/tests/data/Reader/XLS/HiddenMergeCellsTest.xls b/tests/data/Reader/XLS/HiddenMergeCellsTest.xls
new file mode 100644
index 00000000..fefbcecc
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diff --git a/tests/data/Reader/XLSX/HiddenMergeCellsTest.xlsx b/tests/data/Reader/XLSX/HiddenMergeCellsTest.xlsx
new file mode 100644
index 00000000..124f0561
Binary files /dev/null and b/tests/data/Reader/XLSX/HiddenMergeCellsTest.xlsx differ