diff --git a/src/TypeMapper.php b/src/TypeMapper.php
index 95c8567..2184508 100644
--- a/src/TypeMapper.php
+++ b/src/TypeMapper.php
@@ -93,7 +93,7 @@ public function mapGraphQLTypeToPHPType(Type $type, ?bool $nullable = null, bool
         }
 
         if ($type instanceof ListOfType) {
-            return SymfonyType::list($this->mapGraphQLTypeToPHPType($type->getWrappedType(), $builtInOnly));
+            return SymfonyType::list($this->mapGraphQLTypeToPHPType($type->getWrappedType(), null, $builtInOnly));
         }
 
         if ($type instanceof ScalarType) {
diff --git a/tests/ListScalar/Generated/Query/Test/Data.php b/tests/ListScalar/Generated/Query/Test/Data.php
new file mode 100644
index 0000000..a4f0114
--- /dev/null
+++ b/tests/ListScalar/Generated/Query/Test/Data.php
@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ruudk\GraphQLCodeGenerator\ListScalar\Generated\Query\Test;
+
+use Ruudk\GraphQLCodeGenerator\ListScalar\Generated\Query\Test\Data\Wallet;
+use Ruudk\GraphQLCodeGenerator\ListScalar\ValueObjects\Currency;
+
+// This file was automatically generated and should not be edited.
+
+final class Data
+{
+    /**
+     * @var list<Currency>
+     */
+    public array $supportedCurrencies {
+        get => $this->supportedCurrencies ??= array_map(fn($item) => new Currency($item), $this->data['supportedCurrencies']);
+    }
+
+    public Wallet $wallet {
+        get => $this->wallet ??= new Wallet($this->data['wallet']);
+    }
+
+    /**
+     * @var list<Error>
+     */
+    public readonly array $errors;
+
+    /**
+     * @param array{
+     *     'supportedCurrencies': list<string>,
+     *     'wallet': array{
+     *         'currencies': list<string>,
+     *         'name': string,
+     *     },
+     * } $data
+     * @param list<array{
+     *     'code': string,
+     *     'debugMessage'?: string,
+     *     'message': string,
+     * }> $errors
+     */
+    public function __construct(
+        private readonly array $data,
+        array $errors,
+    ) {
+        $this->errors = array_map(fn(array $error) => new Error($error), $errors);
+    }
+}
diff --git a/tests/ListScalar/Generated/Query/Test/Data/Wallet.php b/tests/ListScalar/Generated/Query/Test/Data/Wallet.php
new file mode 100644
index 0000000..ad02de8
--- /dev/null
+++ b/tests/ListScalar/Generated/Query/Test/Data/Wallet.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ruudk\GraphQLCodeGenerator\ListScalar\Generated\Query\Test\Data;
+
+use Ruudk\GraphQLCodeGenerator\ListScalar\ValueObjects\Currency;
+
+// This file was automatically generated and should not be edited.
+
+final class Wallet
+{
+    /**
+     * @var list<Currency>
+     */
+    public array $currencies {
+        get => $this->currencies ??= array_map(fn($item) => new Currency($item), $this->data['currencies']);
+    }
+
+    public string $name {
+        get => $this->name ??= $this->data['name'];
+    }
+
+    /**
+     * @param array{
+     *     'currencies': list<string>,
+     *     'name': string,
+     * } $data
+     */
+    public function __construct(
+        private readonly array $data,
+    ) {}
+}
diff --git a/tests/ListScalar/Generated/Query/Test/Error.php b/tests/ListScalar/Generated/Query/Test/Error.php
new file mode 100644
index 0000000..6e0a888
--- /dev/null
+++ b/tests/ListScalar/Generated/Query/Test/Error.php
@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ruudk\GraphQLCodeGenerator\ListScalar\Generated\Query\Test;
+
+// This file was automatically generated and should not be edited.
+
+final readonly class Error
+{
+    public string $message;
+
+    /**
+     * @param array{
+     *     'debugMessage'?: string,
+     *     'message': string,
+     * } $error
+     */
+    public function __construct(array $error)
+    {
+        $this->message = $error['debugMessage'] ?? $error['message'];
+    }
+}
diff --git a/tests/ListScalar/Generated/Query/Test/TestQuery.php b/tests/ListScalar/Generated/Query/Test/TestQuery.php
new file mode 100644
index 0000000..c7053b3
--- /dev/null
+++ b/tests/ListScalar/Generated/Query/Test/TestQuery.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ruudk\GraphQLCodeGenerator\ListScalar\Generated\Query\Test;
+
+use Ruudk\GraphQLCodeGenerator\TestClient;
+
+// This file was automatically generated and should not be edited.
+
+final readonly class TestQuery {
+    public const string OPERATION_NAME = 'Test';
+    public const string OPERATION_DEFINITION = <<<'GRAPHQL'
+        query Test {
+          supportedCurrencies
+          wallet {
+            name
+            currencies
+          }
+        }
+        
+        GRAPHQL;
+
+    public function __construct(
+        private TestClient $client,
+    ) {}
+
+    public function execute() : Data
+    {
+        $data = $this->client->graphql(
+            self::OPERATION_DEFINITION,
+            [
+            ],
+            self::OPERATION_NAME,
+        );
+
+        return new Data(
+            $data['data'] ?? [], // @phpstan-ignore argument.type
+            $data['errors'] ?? [] // @phpstan-ignore argument.type
+        );
+    }
+}
diff --git a/tests/ListScalar/ListScalarTest.php b/tests/ListScalar/ListScalarTest.php
new file mode 100644
index 0000000..68477f3
--- /dev/null
+++ b/tests/ListScalar/ListScalarTest.php
@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ruudk\GraphQLCodeGenerator\ListScalar;
+
+use Override;
+use Ruudk\GraphQLCodeGenerator\Config\Config;
+use Ruudk\GraphQLCodeGenerator\GraphQLTestCase;
+use Ruudk\GraphQLCodeGenerator\ListScalar\Generated\Query\Test\TestQuery;
+use Ruudk\GraphQLCodeGenerator\ListScalar\ValueObjects\Currency;
+use Symfony\Component\TypeInfo\Type;
+
+/**
+ * Test that lists of custom scalars are correctly typed in the generated code.
+ *
+ * This tests the fix for a bug where the $builtInOnly parameter was not correctly
+ * passed when processing ListOfType in TypeMapper::mapGraphQLTypeToPHPType().
+ *
+ * The bug caused the $data parameter docblock to incorrectly use the PHP mapped type
+ * (e.g., Currency) instead of the primitive JSON type (e.g., string) for list items.
+ */
+final class ListScalarTest extends GraphQLTestCase
+{
+    #[Override]
+    public function getConfig() : Config
+    {
+        return parent::getConfig()
+            ->withScalar('Currency', Type::string(), Type::object(Currency::class));
+    }
+
+    public function testGenerate() : void
+    {
+        $this->assertActualMatchesExpected();
+    }
+
+    public function testQueryWithListOfScalars() : void
+    {
+        $result = new TestQuery($this->getClient([
+            'data' => [
+                'supportedCurrencies' => ['EUR', 'USD', 'GBP'],
+                'wallet' => [
+                    'name' => 'My Wallet',
+                    'currencies' => ['EUR', 'USD'],
+                ],
+            ],
+        ]))->execute();
+
+        // Verify the list of currencies is correctly converted to Currency objects
+        self::assertCount(3, $result->supportedCurrencies);
+        self::assertSame('EUR', $result->supportedCurrencies[0]->code);
+        self::assertSame('USD', $result->supportedCurrencies[1]->code);
+        self::assertSame('GBP', $result->supportedCurrencies[2]->code);
+
+        // Verify nested list of currencies
+        self::assertSame('My Wallet', $result->wallet->name);
+        self::assertCount(2, $result->wallet->currencies);
+        self::assertSame('EUR', $result->wallet->currencies[0]->code);
+        self::assertSame('USD', $result->wallet->currencies[1]->code);
+    }
+}
diff --git a/tests/ListScalar/Schema.graphql b/tests/ListScalar/Schema.graphql
new file mode 100644
index 0000000..461b2e7
--- /dev/null
+++ b/tests/ListScalar/Schema.graphql
@@ -0,0 +1,11 @@
+scalar Currency
+
+type Query {
+    supportedCurrencies: [Currency!]!
+    wallet: Wallet!
+}
+
+type Wallet {
+    name: String!
+    currencies: [Currency!]!
+}
diff --git a/tests/ListScalar/Test.graphql b/tests/ListScalar/Test.graphql
new file mode 100644
index 0000000..a18d229
--- /dev/null
+++ b/tests/ListScalar/Test.graphql
@@ -0,0 +1,7 @@
+query Test {
+    supportedCurrencies
+    wallet {
+        name
+        currencies
+    }
+}
diff --git a/tests/ListScalar/ValueObjects/Currency.php b/tests/ListScalar/ValueObjects/Currency.php
new file mode 100644
index 0000000..7e59f9c
--- /dev/null
+++ b/tests/ListScalar/ValueObjects/Currency.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ruudk\GraphQLCodeGenerator\ListScalar\ValueObjects;
+
+use InvalidArgumentException;
+use JsonSerializable;
+use Override;
+use Stringable;
+
+final readonly class Currency implements JsonSerializable, Stringable
+{
+    public function __construct(
+        public string $code,
+    ) {
+        if (strlen($code) !== 3) {
+            throw new InvalidArgumentException('Currency code must be 3 characters');
+        }
+    }
+
+    #[Override]
+    public function jsonSerialize() : string
+    {
+        return $this->code;
+    }
+
+    #[Override]
+    public function __toString() : string
+    {
+        return $this->code;
+    }
+}