diff --git a/src/Doctrine/Common/Filter/OpenApiFilterTrait.php b/src/Doctrine/Common/Filter/OpenApiFilterTrait.php
index 2af0d951df3..77cc76b5ff4 100644
--- a/src/Doctrine/Common/Filter/OpenApiFilterTrait.php
+++ b/src/Doctrine/Common/Filter/OpenApiFilterTrait.php
@@ -24,26 +24,25 @@ trait OpenApiFilterTrait
     public function getOpenApiParameters(Parameter $parameter): OpenApiParameter|array|null
     {
         $schema = $parameter->getSchema();
-        if (false === $parameter->getCastToArray() || (isset($schema['type']) && 'array' !== $schema['type'])) {
-            return new OpenApiParameter(name: $parameter->getKey(), in: 'query');
-        }
+        $castToArray = $parameter->getCastToArray();
 
-        if ('array' === ($schema['type'] ?? null)) {
-            $arraySchema = $schema;
-        } else {
-            $arraySchema = ['type' => 'array', 'items' => $schema ?? ['type' => 'string']];
+        if (false === $castToArray) {
+            return new OpenApiParameter(name: $parameter->getKey(), in: 'query', schema: $schema ?? []);
         }
 
+        $arraySchema = 'array' === ($schema['type'] ?? null)
+            ? $schema
+            : ['type' => 'array', 'items' => $schema ?? ['type' => 'string']];
         $arrayParameter = new OpenApiParameter(name: $parameter->getKey().'[]', in: 'query', style: 'deepObject', explode: true, schema: $arraySchema);
 
-        // When castToArray is null (default), both singular and array forms are accepted
-        if (null === $parameter->getCastToArray()) {
-            return [
-                new OpenApiParameter(name: $parameter->getKey(), in: 'query'),
-                $arrayParameter,
-            ];
+        if (true === $castToArray) {
+            return $arrayParameter;
         }
 
-        return $arrayParameter;
+        // When castToArray is null (default), both singular and array forms are accepted.
+        return [
+            new OpenApiParameter(name: $parameter->getKey(), in: 'query', schema: $schema ?? []),
+            $arrayParameter,
+        ];
     }
 }
diff --git a/tests/Fixtures/TestBundle/ApiResource/ExactFilterSchemaParameter/ExactFilterSchemaParameter.php b/tests/Fixtures/TestBundle/ApiResource/ExactFilterSchemaParameter/ExactFilterSchemaParameter.php
new file mode 100644
index 00000000000..98269b3741e
--- /dev/null
+++ b/tests/Fixtures/TestBundle/ApiResource/ExactFilterSchemaParameter/ExactFilterSchemaParameter.php
@@ -0,0 +1,69 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <dunglas@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\ExactFilterSchemaParameter;
+
+use ApiPlatform\Doctrine\Orm\Filter\ExactFilter;
+use ApiPlatform\Metadata\GetCollection;
+use ApiPlatform\Metadata\Operation;
+use ApiPlatform\Metadata\QueryParameter;
+
+#[GetCollection(
+    uriTemplate: '/exact_filter_schema_parameters',
+    normalizationContext: ['hydra_prefix' => false],
+    parameters: [
+        // Scalar schema, default castToArray (null) -> both singular and array variants.
+        'code' => new QueryParameter(
+            filter: new ExactFilter(),
+            property: 'code',
+            schema: ['type' => 'integer'],
+        ),
+        // Scalar schema, castToArray: true -> array variant only.
+        'codeArrayCast' => new QueryParameter(
+            filter: new ExactFilter(),
+            property: 'code',
+            schema: ['type' => 'integer'],
+            castToArray: true,
+        ),
+        // Scalar schema, castToArray: false -> singular variant only.
+        'codeNoArray' => new QueryParameter(
+            filter: new ExactFilter(),
+            property: 'code',
+            schema: ['type' => 'integer'],
+            castToArray: false,
+        ),
+        // Already an array schema, castToArray: true -> single array variant, no duplicate.
+        'codeExplicitArray' => new QueryParameter(
+            filter: new ExactFilter(),
+            property: 'code',
+            schema: ['type' => 'array', 'items' => ['type' => 'integer']],
+            castToArray: true,
+        ),
+    ],
+    provider: [self::class, 'provide'],
+)]
+class ExactFilterSchemaParameter
+{
+    public function __construct(
+        public int $code = 0,
+    ) {
+    }
+
+    /**
+     * @return self[]
+     */
+    public static function provide(Operation $operation): array
+    {
+        return [];
+    }
+}
diff --git a/tests/Functional/Parameters/ExactFilterSchemaParameterTest.php b/tests/Functional/Parameters/ExactFilterSchemaParameterTest.php
new file mode 100644
index 00000000000..594df8891cb
--- /dev/null
+++ b/tests/Functional/Parameters/ExactFilterSchemaParameterTest.php
@@ -0,0 +1,99 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <dunglas@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Tests\Functional\Parameters;
+
+use ApiPlatform\Symfony\Bundle\Test\ApiTestCase;
+use ApiPlatform\Tests\Fixtures\TestBundle\ApiResource\ExactFilterSchemaParameter\ExactFilterSchemaParameter;
+use ApiPlatform\Tests\SetupClassResourcesTrait;
+
+final class ExactFilterSchemaParameterTest extends ApiTestCase
+{
+    use SetupClassResourcesTrait;
+
+    protected static ?bool $alwaysBootKernel = false;
+
+    /**
+     * @return class-string[]
+     */
+    public static function getResources(): array
+    {
+        return [ExactFilterSchemaParameter::class];
+    }
+
+    /**
+     * @return array<string, array{name: string, schema: array<string, mixed>}>
+     */
+    private function getOpenApiParametersByName(): array
+    {
+        $response = self::createClient()->request('GET', '/docs', [
+            'headers' => ['Accept' => 'application/vnd.openapi+json'],
+        ]);
+        $this->assertResponseIsSuccessful();
+        $openApiDoc = $response->toArray();
+
+        $parameters = $openApiDoc['paths']['/exact_filter_schema_parameters']['get']['parameters'];
+
+        $byName = [];
+        foreach ($parameters as $parameter) {
+            $byName[$parameter['name']] = $parameter;
+        }
+
+        return $byName;
+    }
+
+    public function testScalarSchemaWithDefaultCastToArrayExposesBothVariants(): void
+    {
+        $parameters = $this->getOpenApiParametersByName();
+
+        $this->assertArrayHasKey('code', $parameters);
+        $this->assertArrayHasKey('code[]', $parameters);
+
+        $this->assertSame('integer', $parameters['code']['schema']['type']);
+
+        $this->assertSame('array', $parameters['code[]']['schema']['type']);
+        $this->assertSame('integer', $parameters['code[]']['schema']['items']['type']);
+    }
+
+    public function testScalarSchemaWithCastToArrayTrueExposesArrayVariantOnly(): void
+    {
+        $parameters = $this->getOpenApiParametersByName();
+
+        $this->assertArrayNotHasKey('codeArrayCast', $parameters);
+        $this->assertArrayHasKey('codeArrayCast[]', $parameters);
+
+        $this->assertSame('array', $parameters['codeArrayCast[]']['schema']['type']);
+        $this->assertSame('integer', $parameters['codeArrayCast[]']['schema']['items']['type']);
+    }
+
+    public function testScalarSchemaWithCastToArrayFalseExposesSingularVariantOnly(): void
+    {
+        $parameters = $this->getOpenApiParametersByName();
+
+        $this->assertArrayHasKey('codeNoArray', $parameters);
+        $this->assertArrayNotHasKey('codeNoArray[]', $parameters);
+
+        $this->assertSame('integer', $parameters['codeNoArray']['schema']['type']);
+    }
+
+    public function testArraySchemaWithCastToArrayTrueExposesSingleArrayVariant(): void
+    {
+        $parameters = $this->getOpenApiParametersByName();
+
+        $this->assertArrayNotHasKey('codeExplicitArray', $parameters);
+        $this->assertArrayHasKey('codeExplicitArray[]', $parameters);
+
+        $this->assertSame('array', $parameters['codeExplicitArray[]']['schema']['type']);
+        $this->assertSame('integer', $parameters['codeExplicitArray[]']['schema']['items']['type']);
+    }
+}