diff --git a/src/PhpSpreadsheet/Reader/Xlsx.php b/src/PhpSpreadsheet/Reader/Xlsx.php
index 2e1ea196b..ffb6c34dc 100644
--- a/src/PhpSpreadsheet/Reader/Xlsx.php
+++ b/src/PhpSpreadsheet/Reader/Xlsx.php
@@ -1492,7 +1492,13 @@ class Xlsx extends BaseReader
                                                         $shadow->setAlignment(self::getArrayItemString(self::getAttributes($outerShdw), 'algn'));
                                                         $clr = $outerShdw->srgbClr ?? $outerShdw->prstClr;
                                                         $shadow->getColor()->setRGB(self::getArrayItemString(self::getAttributes($clr), 'val'));
-                                                        $shadow->setAlpha(self::getArrayItem(self::getAttributes($clr->alpha), 'val') / 1000); // @phpstan-ignore-line
+                                                        if ($clr->alpha) {
+                                                            $alpha = StringHelper::convertToString(self::getArrayItem(self::getAttributes($clr->alpha), 'val'));
+                                                            if (is_numeric($alpha)) {
+                                                                $alpha = (int) ($alpha / 1000);
+                                                                $shadow->setAlpha($alpha);
+                                                            }
+                                                        }
                                                     }
 
                                                     $this->readHyperLinkDrawing($objDrawing, $oneCellAnchor, $hyperlinks);
@@ -1597,7 +1603,13 @@ class Xlsx extends BaseReader
                                                         $shadow->setAlignment(self::getArrayItemString(self::getAttributes($outerShdw), 'algn'));
                                                         $clr = $outerShdw->srgbClr ?? $outerShdw->prstClr;
                                                         $shadow->getColor()->setRGB(self::getArrayItemString(self::getAttributes($clr), 'val'));
-                                                        $shadow->setAlpha(self::getArrayItem(self::getAttributes($clr->alpha), 'val') / 1000); // @phpstan-ignore-line
+                                                        if ($clr->alpha) {
+                                                            $alpha = StringHelper::convertToString(self::getArrayItem(self::getAttributes($clr->alpha), 'val'));
+                                                            if (is_numeric($alpha)) {
+                                                                $alpha = (int) ($alpha / 1000);
+                                                                $shadow->setAlpha($alpha);
+                                                            }
+                                                        }
                                                     }
 
                                                     $this->readHyperLinkDrawing($objDrawing, $twoCellAnchor, $hyperlinks);
diff --git a/tests/PhpSpreadsheetTests/Reader/Xlsx/Issue4415Test.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/Issue4415Test.php
new file mode 100644
index 000000000..2417e9f22
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/Issue4415Test.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
+
+use PhpOffice\PhpSpreadsheet\Reader\Xlsx as XlsxReader;
+use PHPUnit\Framework\TestCase;
+
+class Issue4415Test extends TestCase
+{
+    private static string $file = 'tests/data/Reader/XLSX/issue.4415.xlsx';
+
+    public function testPreliminaries(): void
+    {
+        $file = 'zip://';
+        $file .= self::$file;
+        $file .= '#xl/drawings/drawing1.xml';
+        $data = file_get_contents($file) ?: '';
+        $expected = '<a:alpha val="72600"/>';
+        self::assertStringContainsString($expected, $data);
+        $expected = '<a:alpha val="90100"/>';
+        self::assertStringContainsString($expected, $data);
+        self::assertSame(2, substr_count($data, '<a:alpha '), 'number of drawings with alpha');
+        self::assertSame(2, substr_count($data, '<xdr:oneCellAnchor>'), 'first 2 drawings');
+        self::assertSame(1, substr_count($data, '<xdr:twoCellAnchor>'), 'third drawings');
+    }
+
+    public function testFractionalAlpha(): void
+    {
+        $file = self::$file;
+        $reader = new XlsxReader();
+        $spreadsheet = $reader->load($file);
+        $sheet = $spreadsheet->getActiveSheet();
+        $drawings = $sheet->getDrawingCollection();
+        self::assertCount(3, $drawings);
+        self::assertNotNull($drawings[0]);
+        self::assertNotNull($drawings[1]);
+        self::assertNotNull($drawings[2]);
+        self::assertSame(50, $drawings[0]->getShadow()->getAlpha());
+        self::assertSame(72, $drawings[1]->getShadow()->getAlpha());
+        self::assertSame('', $drawings[1]->getCoordinates2(), 'one cell anchor');
+        self::assertSame(90, $drawings[2]->getShadow()->getAlpha());
+        self::assertNotEquals('', $drawings[2]->getCoordinates2(), 'two cell anchor');
+        $spreadsheet->disconnectWorksheets();
+    }
+}
diff --git a/tests/data/Reader/XLSX/issue.4415.xlsx b/tests/data/Reader/XLSX/issue.4415.xlsx
new file mode 100644
index 000000000..2b970b318
Binary files /dev/null and b/tests/data/Reader/XLSX/issue.4415.xlsx differ