diff --git a/src/PhpSpreadsheet/Reader/Xls.php b/src/PhpSpreadsheet/Reader/Xls.php
index b206f8ac..3f383b9e 100644
--- a/src/PhpSpreadsheet/Reader/Xls.php
+++ b/src/PhpSpreadsheet/Reader/Xls.php
@@ -3622,7 +3622,9 @@ class Xls extends BaseReader
                 $this->phpSheet->getColumnDimensionByColumn($i)->setVisible(!$isHidden);
                 $this->phpSheet->getColumnDimensionByColumn($i)->setOutlineLevel($level);
                 $this->phpSheet->getColumnDimensionByColumn($i)->setCollapsed($isCollapsed);
-                $this->phpSheet->getColumnDimensionByColumn($i)->setXfIndex($this->mapCellXfIndex[$xfIndex]);
+                if (isset($this->mapCellXfIndex[$xfIndex])) {
+                    $this->phpSheet->getColumnDimensionByColumn($i)->setXfIndex($this->mapCellXfIndex[$xfIndex]);
+                }
             }
         }
     }
@@ -3731,7 +3733,7 @@ class Xls extends BaseReader
             $numValue = self::getIEEE754($rknum);
 
             $cell = $this->phpSheet->getCell($columnString . ($row + 1));
-            if (!$this->readDataOnly) {
+            if (!$this->readDataOnly && isset($this->mapCellXfIndex[$xfIndex])) {
                 // add style information
                 $cell->setXfIndex($this->mapCellXfIndex[$xfIndex]);
             }
@@ -3866,7 +3868,7 @@ class Xls extends BaseReader
                 // offset: var; size: 4; RK value
                 $numValue = self::getIEEE754(self::getInt4d($recordData, $offset + 2));
                 $cell = $this->phpSheet->getCell($columnString . ($row + 1));
-                if (!$this->readDataOnly) {
+                if (!$this->readDataOnly && isset($this->mapCellXfIndex[$xfIndex])) {
                     // add style
                     $cell->setXfIndex($this->mapCellXfIndex[$xfIndex]);
                 }
@@ -3910,7 +3912,7 @@ class Xls extends BaseReader
             $numValue = self::extractNumber(substr($recordData, 6, 8));
 
             $cell = $this->phpSheet->getCell($columnString . ($row + 1));
-            if (!$this->readDataOnly) {
+            if (!$this->readDataOnly && isset($this->mapCellXfIndex[$xfIndex])) {
                 // add cell style
                 $cell->setXfIndex($this->mapCellXfIndex[$xfIndex]);
             }
@@ -4018,7 +4020,7 @@ class Xls extends BaseReader
             }
 
             $cell = $this->phpSheet->getCell($columnString . ($row + 1));
-            if (!$this->readDataOnly) {
+            if (!$this->readDataOnly && isset($this->mapCellXfIndex[$xfIndex])) {
                 // add cell style
                 $cell->setXfIndex($this->mapCellXfIndex[$xfIndex]);
             }
@@ -4156,7 +4158,7 @@ class Xls extends BaseReader
                     break;
             }
 
-            if (!$this->readDataOnly) {
+            if (!$this->readDataOnly && isset($this->mapCellXfIndex[$xfIndex])) {
                 // add cell style
                 $cell->setXfIndex($this->mapCellXfIndex[$xfIndex]);
             }
@@ -4194,7 +4196,9 @@ class Xls extends BaseReader
                 // Read cell?
                 if (($this->getReadFilter() !== null) && $this->getReadFilter()->readCell($columnString, $row + 1, $this->phpSheet->getTitle())) {
                     $xfIndex = self::getUInt2d($recordData, 4 + 2 * $i);
-                    $this->phpSheet->getCell($columnString . ($row + 1))->setXfIndex($this->mapCellXfIndex[$xfIndex]);
+                    if (isset($this->mapCellXfIndex[$xfIndex])) {
+                        $this->phpSheet->getCell($columnString . ($row + 1))->setXfIndex($this->mapCellXfIndex[$xfIndex]);
+                    }
                 }
             }
         }
@@ -4245,7 +4249,7 @@ class Xls extends BaseReader
                 $cell = $this->phpSheet->getCell($columnString . ($row + 1));
                 $cell->setValueExplicit($value, DataType::TYPE_STRING);
 
-                if (!$this->readDataOnly) {
+                if (!$this->readDataOnly && isset($this->mapCellXfIndex[$xfIndex])) {
                     // add cell style
                     $cell->setXfIndex($this->mapCellXfIndex[$xfIndex]);
                 }
@@ -4277,7 +4281,7 @@ class Xls extends BaseReader
             $xfIndex = self::getUInt2d($recordData, 4);
 
             // add style information
-            if (!$this->readDataOnly && $this->readEmptyCells) {
+            if (!$this->readDataOnly && $this->readEmptyCells && isset($this->mapCellXfIndex[$xfIndex])) {
                 $this->phpSheet->getCell($columnString . ($row + 1))->setXfIndex($this->mapCellXfIndex[$xfIndex]);
             }
         }
diff --git a/tests/PhpSpreadsheetTests/Reader/XlsTest.php b/tests/PhpSpreadsheetTests/Reader/XlsTest.php
index 77ad91fa..da39f8b2 100644
--- a/tests/PhpSpreadsheetTests/Reader/XlsTest.php
+++ b/tests/PhpSpreadsheetTests/Reader/XlsTest.php
@@ -3,9 +3,9 @@
 namespace PhpOffice\PhpSpreadsheetTests\Reader;
 
 use PhpOffice\PhpSpreadsheet\Reader\Xls;
-use PHPUnit\Framework\TestCase;
+use PhpOffice\PhpSpreadsheetTests\Functional\AbstractFunctional;
 
-class XlsTest extends TestCase
+class XlsTest extends AbstractFunctional
 {
     /**
      * Test load Xls file.
@@ -17,4 +17,30 @@ class XlsTest extends TestCase
         $spreadsheet = $reader->load($filename);
         self::assertEquals('Title', $spreadsheet->getSheet(0)->getCell('A1')->getValue());
     }
+
+    /**
+     * Test load Xls file with invalid xfIndex.
+     */
+    public function testLoadXlsBug1505(): void
+    {
+        $filename = 'tests/data/Reader/XLS/bug1505.xls';
+        $reader = new Xls();
+        $spreadsheet = $reader->load($filename);
+        $sheet = $spreadsheet->getActiveSheet();
+        $col = $sheet->getHighestColumn();
+        $row = $sheet->getHighestRow();
+
+        $newspreadsheet = $this->writeAndReload($spreadsheet, 'Xlsx');
+        $newsheet = $newspreadsheet->getActiveSheet();
+        $newcol = $newsheet->getHighestColumn();
+        $newrow = $newsheet->getHighestRow();
+
+        self::assertEquals($spreadsheet->getSheetCount(), $newspreadsheet->getSheetCount());
+        self::assertEquals($sheet->getTitle(), $newsheet->getTitle());
+        self::assertEquals($sheet->getColumnDimensions(), $newsheet->getColumnDimensions());
+        self::assertEquals($col, $newcol);
+        self::assertEquals($row, $newrow);
+        self::assertEquals($sheet->getCell('A1')->getFormattedValue(), $newsheet->getCell('A1')->getFormattedValue());
+        self::assertEquals($sheet->getCell("$col$row")->getFormattedValue(), $newsheet->getCell("$col$row")->getFormattedValue());
+    }
 }
diff --git a/tests/data/Reader/XLS/bug1505.xls b/tests/data/Reader/XLS/bug1505.xls
new file mode 100644
index 00000000..3440ceb9
Binary files /dev/null and b/tests/data/Reader/XLS/bug1505.xls differ