diff --git a/src/Metadata/ClassMetadata.php b/src/Metadata/ClassMetadata.php
index 24b176d8..9b3c3083 100644
--- a/src/Metadata/ClassMetadata.php
+++ b/src/Metadata/ClassMetadata.php
@@ -5,6 +5,7 @@
 namespace Patchlevel\Hydrator\Metadata;
 
 use ReflectionClass;
+use ReflectionParameter;
 
 /**
  * @phpstan-type serialized array{
@@ -23,6 +24,9 @@ final class ClassMetadata
     /** @var array<string, PropertyMetadata> */
     public readonly array $properties;
 
+    /** @var array<string, ReflectionParameter>|null */
+    private array|null $promotedConstructorDefaults = null;
+
     /**
      * @param ReflectionClass<T>     $reflection
      * @param list<PropertyMetadata> $properties
@@ -62,6 +66,32 @@ public function newInstance(): object
         return $this->reflection->newInstanceWithoutConstructor();
     }
 
+    /** @return array<string, ReflectionParameter> */
+    public function promotedConstructorDefaults(): array
+    {
+        if ($this->promotedConstructorDefaults !== null) {
+            return $this->promotedConstructorDefaults;
+        }
+
+        $constructor = $this->reflection->getConstructor();
+
+        if (!$constructor) {
+            return $this->promotedConstructorDefaults = [];
+        }
+
+        $result = [];
+
+        foreach ($constructor->getParameters() as $parameter) {
+            if (!$parameter->isPromoted() || !$parameter->isDefaultValueAvailable()) {
+                continue;
+            }
+
+            $result[$parameter->getName()] = $parameter;
+        }
+
+        return $this->promotedConstructorDefaults = $result;
+    }
+
     /** @return serialized */
     public function __serialize(): array
     {
diff --git a/src/Middleware/TransformMiddleware.php b/src/Middleware/TransformMiddleware.php
index d9464c2a..c8c44fa0 100644
--- a/src/Middleware/TransformMiddleware.php
+++ b/src/Middleware/TransformMiddleware.php
@@ -9,7 +9,6 @@
 use Patchlevel\Hydrator\Metadata\ClassMetadata;
 use Patchlevel\Hydrator\NormalizationFailure;
 use Patchlevel\Hydrator\TypeMismatch;
-use ReflectionParameter;
 use Throwable;
 use TypeError;
 
@@ -43,9 +42,7 @@ public function hydrate(ClassMetadata $metadata, array $data, array $context, St
                     continue;
                 }
 
-                if ($constructorParameters === null) {
-                    $constructorParameters = $this->promotedConstructorParametersWithDefaultValue($metadata);
-                }
+                $constructorParameters ??= $metadata->promotedConstructorDefaults();
 
                 if (!array_key_exists($propertyMetadata->propertyName, $constructorParameters)) {
                     continue;
@@ -138,31 +135,4 @@ public function extract(ClassMetadata $metadata, object $object, array $context,
 
         return $data;
     }
-
-    /** @return array<string, ReflectionParameter> */
-    private function promotedConstructorParametersWithDefaultValue(ClassMetadata $metadata): array
-    {
-        $constructor = $metadata->reflection->getConstructor();
-
-        if (!$constructor) {
-            return [];
-        }
-
-        $parameters = $constructor->getParameters();
-        $result = [];
-
-        foreach ($parameters as $parameter) {
-            if (!$parameter->isPromoted()) {
-                continue;
-            }
-
-            if (!$parameter->isDefaultValueAvailable()) {
-                continue;
-            }
-
-            $result[$parameter->getName()] = $parameter;
-        }
-
-        return $result;
-    }
 }