diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1308f94..20dba90 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ Updates should follow the [Keep a CHANGELOG](http://keepachangelog.com/) princip
 ### Fixed
 - Fixed a missing auth header during customer token generation
 - Fixed the config reader to return the correct value when falsy values are configured (e.g. 0, 'false')
+- Fixed compatibility to PHP 8.0
 ### Added
 - Allowed manual and individual adding of positions which are not related to an article
 
diff --git a/src/Components/Transformer/LineItemTransformer.php b/src/Components/Transformer/LineItemTransformer.php
index bd4fb06..e1c6932 100644
--- a/src/Components/Transformer/LineItemTransformer.php
+++ b/src/Components/Transformer/LineItemTransformer.php
@@ -292,10 +292,14 @@ public function createShippingLineItem($shippingCostsWithTax, $shippingCostsNet,
      */
     public function getUnitPriceWithTax(array $lineItem): float
     {
-        $netPriceIsShown = isset($lineItem['amountWithTax']) ? true : false;
+        $netPrice = $lineItem['amountWithTax'] ?? null;
 
-        if ($netPriceIsShown) {
-            return round(str_replace(',', '.', $lineItem['amountWithTax']) / $lineItem['quantity'], 2);
+        if ($netPrice !== null) {
+            if (is_string($netPrice)) {
+                $netPrice = (float) str_replace(',', '.', $lineItem['amountWithTax']);
+            }
+
+            return round($netPrice / $lineItem['quantity'], 2);
         }
 
         return (float) $lineItem['priceNumeric'];