diff --git a/src/Prophecy/Doubler/Generator/ClassCodeGenerator.php b/src/Prophecy/Doubler/Generator/ClassCodeGenerator.php
index 2d30a3f2e..ddc6985cd 100644
--- a/src/Prophecy/Doubler/Generator/ClassCodeGenerator.php
+++ b/src/Prophecy/Doubler/Generator/ClassCodeGenerator.php
@@ -110,7 +110,14 @@ private function generateArguments(array $arguments): array
             $php .= '$'.$argument->getName();
 
             if ($argument->isOptional() && !$argument->isVariadic()) {
-                $php .= ' = '.var_export($argument->getDefault(), true);
+                $default = var_export($argument->getDefault(), true);
+
+                // This is necessary for PHP 8.1, as enum cases are exported without a leading slash in this version
+                if ($argument->getDefault() instanceof \UnitEnum && 0 !== strpos($default, '\\'))  {
+                    $default = '\\'.$default;
+                }
+
+                $php .= ' = '.$default;
             }
 
             return $php;