diff --git a/.fernignore b/.fernignore
index 57a0d2f..a1fc620 100644
--- a/.fernignore
+++ b/.fernignore
@@ -1,6 +1,6 @@
 # Specify files that shouldn't be modified by Fern
 LICENSE.md
 CONTRIBUTING.md
-
-# nullable DateTime fix
 src/Core/Json/JsonSerializableType.php
+src/Types/PushPayLinkRequest.php
+tests/Core/Json/NullPropertyTest.php
diff --git a/src/Core/Json/JsonSerializableType.php b/src/Core/Json/JsonSerializableType.php
index 445d0bb..bee9dc7 100644
--- a/src/Core/Json/JsonSerializableType.php
+++ b/src/Core/Json/JsonSerializableType.php
@@ -39,12 +39,12 @@ public function toJson(): string
     }
 
     /**
-     * Serializes the object to an array.
+     * Serializes the object to a JSON-ready value.
      *
-     * @return mixed[] Array representation of the object.
+     * @return array<string,mixed>|\stdClass
      * @throws JsonException If serialization fails.
      */
-    public function jsonSerialize(): array
+    public function jsonSerialize(): array|\stdClass
     {
         $result = [];
         $reflectionClass = new \ReflectionClass($this);
@@ -65,21 +65,24 @@ public function jsonSerialize(): array
             }
 
             // Handle Union annotations
+            $alreadySerialized = false;
             $unionTypeAttr = $property->getAttributes(Union::class)[0] ?? null;
             if ($unionTypeAttr) {
                 $unionType = $unionTypeAttr->newInstance();
                 $value = JsonSerializer::serializeUnion($value, $unionType);
+                $alreadySerialized = true;
             }
 
             // Handle arrays with type annotations
             $arrayTypeAttr = $property->getAttributes(ArrayType::class)[0] ?? null;
-            if ($arrayTypeAttr && is_array($value)) {
+            if (!$alreadySerialized && $arrayTypeAttr && is_array($value)) {
                 $arrayType = $arrayTypeAttr->newInstance()->type;
                 $value = JsonSerializer::serializeArray($value, $arrayType);
+                $alreadySerialized = true;
             }
 
             // Handle object
-            if (is_object($value)) {
+            if (!$alreadySerialized && is_object($value)) {
                 $value = JsonSerializer::serializeObject($value);
             }
 
@@ -88,6 +91,10 @@ public function jsonSerialize(): array
                 $result[$jsonKey] = $value;
             }
         }
+        // Empty object models must serialize to {} (not [])
+        if ($result === []) {
+            return new \stdClass();
+        }
         return $result;
     }
 
diff --git a/src/Types/PushPayLinkRequest.php b/src/Types/PushPayLinkRequest.php
index 51f1b8c..d91240e 100644
--- a/src/Types/PushPayLinkRequest.php
+++ b/src/Types/PushPayLinkRequest.php
@@ -134,16 +134,22 @@ public function jsonSerialize(): array
         $result['channel'] = $this->channel;
 
         $base = parent::jsonSerialize();
-        $result = array_merge($base, $result);
+        if (is_array($base)) {
+            $result = array_merge($base, $result);
+        }
 
         switch ($this->channel) {
             case 'email':
                 $value = $this->asEmail()->jsonSerialize();
-                $result = array_merge($value, $result);
+                if (is_array($value)) {
+                    $result = array_merge($value, $result);
+                }
                 break;
             case 'sms':
                 $value = $this->asSms()->jsonSerialize();
-                $result = array_merge($value, $result);
+                if (is_array($value)) {
+                    $result = array_merge($value, $result);
+                }
                 break;
             case '_unknown':
             default:
@@ -152,9 +158,15 @@ public function jsonSerialize(): array
                 }
                 if ($this->value instanceof JsonSerializableType) {
                     $value = $this->value->jsonSerialize();
-                    $result = array_merge($value, $result);
+                    if (is_array($value)) {
+                        $result = array_merge($value, $result);
+                    }
                 } elseif (is_array($this->value)) {
                     $result = array_merge($this->value, $result);
+                } elseif ($this->value instanceof \stdClass) {
+                    /** @var array<string, mixed> $normalized */
+                    $normalized = (array) $this->value;
+                    $result = array_merge($normalized, $result);
                 }
         }
 
@@ -190,7 +202,9 @@ public static function jsonDeserialize(array $data): static
             case '_unknown':
             default:
                 $args['channel'] = '_unknown';
-                $args['value'] = $data;
+                /** @var array<string, mixed> $unknown */
+                $unknown = $data;
+                $args['value'] = $unknown;
         }
 
         // @phpstan-ignore-next-line
diff --git a/tests/Core/Json/NullPropertyTest.php b/tests/Core/Json/NullPropertyTest.php
index 8f8ee6c..c44668c 100644
--- a/tests/Core/Json/NullPropertyTest.php
+++ b/tests/Core/Json/NullPropertyTest.php
@@ -46,6 +46,7 @@ public function testNullPropertiesAreOmitted(): void
         );
 
         $serialized = $object->jsonSerialize();
+        $this->assertIsArray($serialized, 'Serialized result should be an array.');
         $this->assertArrayHasKey('non_null_property', $serialized, 'non_null_property should be present in the serialized JSON.');
         $this->assertArrayNotHasKey('null_property', $serialized, 'null_property should be omitted from the serialized JSON.');
         $this->assertEquals('Test String', $serialized['non_null_property'], 'non_null_property should have the correct value.');