diff --git a/src/SchemaFactory.php b/src/SchemaFactory.php
index 8f23bf5df6..396cc12122 100644
--- a/src/SchemaFactory.php
+++ b/src/SchemaFactory.php
@@ -78,7 +78,7 @@ class SchemaFactory
     /** @var array<int,string> */
     private array $controllerNamespaces = [];
 
-    /** @var array<int,string> */
+    /** @var array<int, array{ string, bool }> */
     private array $typeNamespaces = [];
 
     /** @var QueryProviderInterface[] */
@@ -142,10 +142,12 @@ public function addControllerNamespace(string $namespace): self
 
     /**
      * Registers a namespace that can contain GraphQL types.
+     *
+     * @param bool $autoload Use autoloading when scanning classes. Set to `false` to use `require_once` instead.
      */
-    public function addTypeNamespace(string $namespace): self
+    public function addTypeNamespace(string $namespace, bool $autoload = true): self
     {
-        $this->typeNamespaces[] = $namespace;
+        $this->typeNamespaces[] = [$namespace, $autoload];
 
         return $this;
     }
@@ -346,7 +348,11 @@ public function createSchema(): Schema
 
         $namespaceFactory = new NamespaceFactory($namespacedCache, $this->classNameMapper, $this->globTTL);
         $nsList = array_map(
-            static fn (string $namespace) => $namespaceFactory->createNamespace($namespace),
+            static function (array $namespacePair) use ($namespaceFactory) {
+                [$namespace, $autoload] = $namespacePair;
+
+                return $namespaceFactory->createNamespace($namespace, autoload: $autoload);
+            },
             $this->typeNamespaces,
         );
 
diff --git a/src/Utils/Namespaces/NS.php b/src/Utils/Namespaces/NS.php
index 4e6fe98d99..5c5f1e94f1 100644
--- a/src/Utils/Namespaces/NS.php
+++ b/src/Utils/Namespaces/NS.php
@@ -22,9 +22,8 @@ final class NS
     /**
      * The array of globbed classes.
      * Only instantiable classes are returned.
-     * Key: fully qualified class name
      *
-     * @var array<string,ReflectionClass<object>>
+     * @var array<class-string, ReflectionClass<object>>
      */
     private array|null $classes = null;
 
@@ -35,6 +34,7 @@ public function __construct(
         private readonly ClassNameMapper $classNameMapper,
         private readonly int|null $globTTL,
         private readonly bool $recursive,
+        private readonly bool $autoload = true,
     ) {
     }
 
@@ -42,7 +42,7 @@ public function __construct(
      * Returns the array of globbed classes.
      * Only instantiable classes are returned.
      *
-     * @return array<class-string,ReflectionClass<object>> Key: fully qualified class name
+     * @return array<class-string, ReflectionClass<object>> Key: fully qualified class name
      */
     public function getClassList(): array
     {
@@ -52,26 +52,14 @@ public function getClassList(): array
             /** @var array<class-string, string> $classes Override class-explorer lib */
             $classes = $explorer->getClassMap();
             foreach ($classes as $className => $phpFile) {
-                if (! class_exists($className, false) && ! interface_exists($className, false)) {
-                    // Let's try to load the file if it was not imported yet.
-                    // We are importing the file manually to avoid triggering the autoloader.
-                    // The autoloader might trigger errors if the file does not respect PSR-4 or if the
-                    // Symfony DebugAutoLoader is installed. (see https://github.com/thecodingmachine/graphqlite/issues/216)
-                    require_once $phpFile;
-                    // Does it exists now?
-                    // @phpstan-ignore-next-line
-                    if (! class_exists($className, false) && ! interface_exists($className, false)) {
-                        continue;
-                    }
+                if (!$this->loadClass($className, $phpFile)) {
+                    continue;
                 }
 
-                $refClass = new ReflectionClass($className);
-
-                $this->classes[$className] = $refClass;
+                $this->classes[$className] = new ReflectionClass($className);
             }
         }
 
-        // @phpstan-ignore-next-line - Not sure why we cannot annotate the $classes above
         return $this->classes;
     }
 
@@ -79,4 +67,32 @@ public function getNamespace(): string
     {
         return $this->namespace;
     }
+
+    /**
+     * Attempt to load a class depending on the @see $autoload setting.
+     *
+     * @param class-string $className
+     */
+    private function loadClass(string $className, string $phpFile): bool
+    {
+        if (class_exists($className, $this->autoload) || interface_exists($className, $this->autoload)) {
+            return true;
+        }
+
+        // If autoloading was requested and there's no class by this name, then it's most likely that the
+        // guessed class name from GlobClassExplorer is simply not a class, so we'll skip it.
+        // See: https://github.com/thecodingmachine/graphqlite/issues/659
+        if ($this->autoload) {
+            return false;
+        }
+
+        // Otherwise attempt to load the file without autoloading.
+        // The autoloader might trigger errors if the file does not respect PSR-4 or if the
+        // Symfony DebugAutoLoader is installed. (see https://github.com/thecodingmachine/graphqlite/issues/216)
+        require_once $phpFile;
+
+        // The class might still not be loaded if guessed class name doesn't match the PHP file,
+        // so we should check if it got loaded after requiring the PHP file.
+        return class_exists($className, false) || interface_exists($className, false);
+    }
 }
diff --git a/src/Utils/Namespaces/NamespaceFactory.php b/src/Utils/Namespaces/NamespaceFactory.php
index 9d1c6d32cf..2559fddf57 100644
--- a/src/Utils/Namespaces/NamespaceFactory.php
+++ b/src/Utils/Namespaces/NamespaceFactory.php
@@ -22,8 +22,15 @@ public function __construct(private readonly CacheInterface $cache, ClassNameMap
     }
 
     /** @param string $namespace A PHP namespace */
-    public function createNamespace(string $namespace, bool $recursive = true): NS
+    public function createNamespace(string $namespace, bool $recursive = true, bool $autoload = true): NS
     {
-        return new NS($namespace, $this->cache, $this->classNameMapper, $this->globTTL, $recursive);
+        return new NS(
+            namespace: $namespace,
+            cache: $this->cache,
+            classNameMapper: $this->classNameMapper,
+            globTTL: $this->globTTL,
+            recursive: $recursive,
+            autoload: $autoload,
+        );
     }
 }
diff --git a/tests/Fixtures/Integration/Models/BadNamespaceClass.php b/tests/Fixtures/BadNamespace/BadNamespaceClass.php
similarity index 100%
rename from tests/Fixtures/Integration/Models/BadNamespaceClass.php
rename to tests/Fixtures/BadNamespace/BadNamespaceClass.php
diff --git a/tests/Utils/Namespaces/NSTest.php b/tests/Utils/Namespaces/NSTest.php
new file mode 100644
index 0000000000..f51e49adae
--- /dev/null
+++ b/tests/Utils/Namespaces/NSTest.php
@@ -0,0 +1,59 @@
+<?php
+
+namespace TheCodingMachine\GraphQLite\Utils\Namespaces;
+
+use Mouf\Composer\ClassNameMapper;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Cache\Adapter\ArrayAdapter;
+use Symfony\Component\Cache\Psr16Cache;
+use TheCodingMachine\GraphQLite\Fixtures\Types\AbstractFooType;
+use TheCodingMachine\GraphQLite\Fixtures\Types\FooExtendType;
+use TheCodingMachine\GraphQLite\Fixtures\Types\FooType;
+use TheCodingMachine\GraphQLite\Fixtures\Types\GetterSetterType;
+use TheCodingMachine\GraphQLite\Fixtures\Types\MagicGetterSetterType;
+use TheCodingMachine\GraphQLite\Fixtures\Types\NoTypeAnnotation;
+use TheCodingMachine\GraphQLite\Fixtures\Types\TestFactory;
+
+class NSTest extends TestCase
+{
+    /**
+     * @dataProvider loadsClassListProvider
+     */
+    public function testLoadsClassList(array $expectedClasses, string $namespace, bool $autoload): void
+    {
+        $ns = new NS(
+            namespace: $namespace,
+            cache: new Psr16Cache(new ArrayAdapter()),
+            classNameMapper: ClassNameMapper::createFromComposerFile(null, null, true),
+            globTTL: null,
+            recursive: true,
+            autoload: $autoload,
+        );
+
+        self::assertSame($expectedClasses, array_keys($ns->getClassList()));
+    }
+
+    public static function loadsClassListProvider(): iterable
+    {
+        yield 'autoload' => [
+            [
+                TestFactory::class,
+                GetterSetterType::class,
+                FooType::class,
+                MagicGetterSetterType::class,
+                FooExtendType::class,
+                NoTypeAnnotation::class,
+                AbstractFooType::class,
+            ],
+            'TheCodingMachine\GraphQLite\Fixtures\Types',
+            true,
+        ];
+
+        // The class should be ignored.
+        yield 'incorrect namespace class without autoload' => [
+            [],
+            'TheCodingMachine\GraphQLite\Fixtures\BadNamespace',
+            false,
+        ];
+    }
+}
\ No newline at end of file