diff --git a/src/PhpSpreadsheet/Reader/Xls.php b/src/PhpSpreadsheet/Reader/Xls.php
index 402fea9f..d1f14ae1 100644
--- a/src/PhpSpreadsheet/Reader/Xls.php
+++ b/src/PhpSpreadsheet/Reader/Xls.php
@@ -3759,8 +3759,13 @@ class Xls extends BaseReader
                         } else {
                             $textRun = $richText->createTextRun($text);
                             if (isset($fmtRuns[$i - 1])) {
-                                $fontIndex = $fmtRuns[$i - 1]['fontIndex'];
-
+                                if ($fmtRuns[$i - 1]['fontIndex'] < 4) {
+                                    $fontIndex = $fmtRuns[$i - 1]['fontIndex'];
+                                } else {
+                                    // this has to do with that index 4 is omitted in all BIFF versions for some stra          nge reason
+                                    // check the OpenOffice documentation of the FONT record
+                                    $fontIndex = $fmtRuns[$i - 1]['fontIndex'] - 1;
+                                }
                                 if (array_key_exists($fontIndex, $this->objFonts) === false) {
                                     $fontIndex = count($this->objFonts) - 1;
                                 }
diff --git a/tests/PhpSpreadsheetTests/Reader/Xls/RichTextSizeTest.php b/tests/PhpSpreadsheetTests/Reader/Xls/RichTextSizeTest.php
new file mode 100644
index 00000000..54274e8c
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Reader/Xls/RichTextSizeTest.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xls;
+
+use PhpOffice\PhpSpreadsheet\Reader\Xls;
+use PhpOffice\PhpSpreadsheetTests\Functional\AbstractFunctional;
+
+class RichTextSizeTest extends AbstractFunctional
+{
+    public function testRichTextRunSize(): void
+    {
+        $filename = 'tests/data/Reader/XLS/RichTextFontSize.xls';
+        $reader = new Xls();
+        $spreadsheet = $reader->load($filename);
+        $sheet = $spreadsheet->getSheetByName('橱柜门板');
+        self::assertNotNull($sheet);
+        $text = $sheet->getCell('L15')->getValue();
+        $elements = $text->getRichTextElements();
+        self::assertEquals(10, $elements[2]->getFont()->getSize());
+        $spreadsheet->disconnectWorksheets();
+    }
+}
diff --git a/tests/data/Reader/XLS/RichTextFontSize.xls b/tests/data/Reader/XLS/RichTextFontSize.xls
new file mode 100644
index 00000000..3edf4737
Binary files /dev/null and b/tests/data/Reader/XLS/RichTextFontSize.xls differ