diff --git a/src/Generator/DefaultArgumentGenerator.php b/src/Generator/DefaultArgumentGenerator.php
index 891c4b77..ef41305a 100644
--- a/src/Generator/DefaultArgumentGenerator.php
+++ b/src/Generator/DefaultArgumentGenerator.php
@@ -88,7 +88,8 @@ trait DefaultArgumentGenerator
                         $code .= 'return ' . $plan->expr . ';' . PHP_EOL;
                     }
                 } else {
-                    $code .= 'return ' . $argInfo->default . ';' . PHP_EOL;
+                    $default = $this->convertRuntimeConstantDefault($type, $argInfo->default);
+                    $code .= 'return ' . $default . ';' . PHP_EOL;
                 }
 
                 $code .= '}' . PHP_EOL . PHP_EOL;
@@ -98,6 +99,28 @@ trait DefaultArgumentGenerator
         return $code;
     }
 
+    /**
+     * Runtime constant lookup returns Variant, but a typed default helper must
+     * return its native C++ type explicitly. Convert the complete expression so
+     * constants nested in expressions are covered as well.
+     */
+    private function convertRuntimeConstantDefault(string $type, string $default): string
+    {
+        if (!str_contains($default, 'php::constant(')) {
+            return $default;
+        }
+
+        return match ($type) {
+            Type::INT => 'php::toInt(' . $default . ')',
+            Type::FLOAT => 'php::toFloat(' . $default . ')',
+            Type::BOOL => 'php::toBool(' . $default . ')',
+            Type::STR => 'php::toString(' . $default . ')',
+            Type::ARRAY => 'php::toArray(' . $default . ')',
+            Type::OBJECT => 'php::toObject(' . $default . ')',
+            default => $default,
+        };
+    }
+
     private function shouldGenerateDefaultArgumentHelper(ArgInfo $argInfo): bool
     {
         if ($argInfo->variadic) {
diff --git a/src/Preprocessor.php b/src/Preprocessor.php
index 3e46799d..877cc4f2 100644
--- a/src/Preprocessor.php
+++ b/src/Preprocessor.php
@@ -83,53 +83,6 @@ class Preprocessor extends CompilerBase
         return $type . ' ' . $argInfo->name;
     }
 
-    /**
-     * A default value that can only be resolved at runtime (e.g. a class/global
-     * constant coming from a class that is not compiled into the binary) is emitted
-     * as a `php::constant(...)` call, which returns a `php::Variant`.
-     *
-     * Copy-initializing a typed (non-Variant) parameter such as `php::Int`,
-     * `php::Float`, `php::Bool`, `php::Str`, `php::Array` or `php::Object` from a
-     * `php::Variant` is rejected by C++ because the conversion is explicit:
-     *
-     *     php::Int type = php::constant(...);   // error C2440
-     *
-     * The function body already converts such values with `php::toInt(...)` /
-     * `php::toFloat(...)` / ... (see convertExprFromType), so we wrap the default
-     * with the very same conversion here. This keeps the declaration consistent with
-     * the body and produces compilable code:
-     *
-     *     php::Int type = php::toInt(php::constant(...));   // OK
-     *
-     * Parameters whose effective type is `php::Var` (including Stream/Box, which are
-     * mapped to `php::Var`) accept a `php::Variant` directly, so they are left alone.
-     */
-    protected function wrapScalarDefaultValue(string $type, string $defaultExpr): string
-    {
-        if (!str_starts_with($defaultExpr, 'php::constant(')) {
-            return $defaultExpr;
-        }
-        $target = $type;
-        if ($target === Type::STREAM || $target === Type::BOX) {
-            $target = Type::VAR;
-        }
-        static $converters = [
-            Type::INT => 'php::toInt',
-            Type::FLOAT => 'php::toFloat',
-            Type::BOOL => 'php::toBool',
-            Type::STR => 'php::toString',
-            Type::ARRAY => 'php::toArray',
-            Type::OBJECT => 'php::toObject',
-            Type::BIGINT => 'php::toBigInt',
-            Type::DECIMAL => 'php::toDecimal',
-            Type::BIGFLOAT => 'php::toBigFloat',
-        ];
-        if (isset($converters[$target])) {
-            return $converters[$target] . '(' . $defaultExpr . ')';
-        }
-        return $defaultExpr;
-    }
-
     public function getCppFile(string $file): string
     {
         $info = pathinfo($file);
@@ -515,8 +468,7 @@ class Preprocessor extends CompilerBase
                         $argInfo->default = 'php::newReference(' . $this->parseParamDefaultValue($param->default) . ')';
                     }
                 } else {
-                    $defaultExpr = $arrayInitPlan ? $arrayInitPlan->expr : $this->parseParamDefaultValue($param->default);
-                    $argInfo->default = $this->wrapScalarDefaultValue($argInfo->type, $defaultExpr);
+                    $argInfo->default = $arrayInitPlan ? $arrayInitPlan->expr : $this->parseParamDefaultValue($param->default);
                     $argInfo->arrayInitPlan = $arrayInitPlan;
                     $argInfo->defaultValue = $param->default;
                 }
diff --git a/tests/compiler/const/class-const-default-value-typed.phpt b/tests/compiler/const/class-const-default-value-typed.phpt
index 7ee526ed..d9b5d26d 100644
--- a/tests/compiler/const/class-const-default-value-typed.phpt
+++ b/tests/compiler/const/class-const-default-value-typed.phpt
@@ -5,14 +5,15 @@ Typed parameter default value from an unresolvable (external) class constant
 
 class TypedDefault
 {
-    // \ArrayObject is an internal (external) class whose constants cannot be folded
-    // at compile time, so the default is emitted as php::constant(...). The parameter
-    // type `int` maps to php::Int, which cannot be copy-initialized from the
-    // php::Variant returned by php::constant(...). The compiler must wrap the default
-    // in php::Int(...) so the generated C++ compiles.
-    public function run(int $value = \ArrayObject::ARRAY_AS_PROPS)
+    public function run(
+        int $value = \ArrayObject::ARRAY_AS_PROPS,
+        float $floatValue = \ArrayObject::ARRAY_AS_PROPS,
+        string $format = \DateTime::ATOM,
+        int $composite = 1 | \ArrayObject::ARRAY_AS_PROPS,
+        mixed $variant = \ArrayObject::STD_PROP_LIST,
+    )
     {
-        var_dump($value);
+        var_dump($value, $floatValue, $format, $composite, $variant);
     }
 }
 
@@ -23,3 +24,7 @@ function main()
 ?>
 --EXPECT--
 int(2)
+float(2)
+string(13) "Y-m-d\TH:i:sP"
+int(3)
+int(1)