diff --git a/src/PhpSpreadsheet/Chart/Axis.php b/src/PhpSpreadsheet/Chart/Axis.php
index 1f5ae152..5f235c3d 100644
--- a/src/PhpSpreadsheet/Chart/Axis.php
+++ b/src/PhpSpreadsheet/Chart/Axis.php
@@ -341,7 +341,7 @@ class Axis extends Properties
         $this->setShadowPresetsProperties((int) $shadowPresets)
             ->setShadowColor(
                 $colorValue === null ? $this->shadowProperties['color']['value'] : $colorValue,
-                $colorAlpha === null ? (int) $this->shadowProperties['color']['alpha'] : $colorAlpha,
+                $colorAlpha === null ? $this->shadowProperties['color']['alpha'] : $colorAlpha,
                 $colorType === null ? $this->shadowProperties['color']['type'] : $colorType
             )
             ->setShadowBlur($blur)
diff --git a/src/PhpSpreadsheet/Chart/GridLines.php b/src/PhpSpreadsheet/Chart/GridLines.php
index ca9ed555..6093a60e 100644
--- a/src/PhpSpreadsheet/Chart/GridLines.php
+++ b/src/PhpSpreadsheet/Chart/GridLines.php
@@ -281,7 +281,7 @@ class GridLines extends Properties
      * @param int $presets
      * @param string $colorValue
      * @param string $colorType
-     * @param int $colorAlpha
+     * @param string $colorAlpha
      * @param string $blur
      * @param int $angle
      * @param float $distance
@@ -292,7 +292,7 @@ class GridLines extends Properties
             ->setShadowPresetsProperties((int) $presets)
             ->setShadowColor(
                 $colorValue === null ? $this->shadowProperties['color']['value'] : $colorValue,
-                $colorAlpha === null ? (int) $this->shadowProperties['color']['alpha'] : $this->getTrueAlpha($colorAlpha),
+                $colorAlpha === null ? $this->shadowProperties['color']['alpha'] : $this->getTrueAlpha($colorAlpha),
                 $colorType === null ? $this->shadowProperties['color']['type'] : $colorType
             )
             ->setShadowBlur($blur)