diff --git a/lib/Doctrine/ORM/Internal/Hydration/HydrationException.php b/lib/Doctrine/ORM/Internal/Hydration/HydrationException.php
index d807c0eca28..d4bc984d8cf 100644
--- a/lib/Doctrine/ORM/Internal/Hydration/HydrationException.php
+++ b/lib/Doctrine/ORM/Internal/Hydration/HydrationException.php
@@ -83,9 +83,8 @@ public static function missingDiscriminatorMetaMappingColumn($entityName, $discr
     }
 
     /**
-     * @param string   $discrValue
-     * @param string[] $discrValues
-     * @psalm-param list<string> $discrValues
+     * @param string           $discrValue
+     * @param list<int|string> $discrValues
      *
      * @return HydrationException
      */
diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
index c33c437f72b..81eaa99bb60 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
@@ -554,9 +554,9 @@ class ClassMetadataInfo implements ClassMetadata
      *
      * @see discriminatorColumn
      *
-     * @var array<string, string>
+     * @var array<int|string, string>
      *
-     * @psalm-var array<string, class-string>
+     * @psalm-var array<int|string, class-string>
      */
     public $discriminatorMap = [];
 
@@ -3254,7 +3254,7 @@ final public function getDiscriminatorColumn(): array
      * Sets the discriminator values used by this class.
      * Used for JOINED and SINGLE_TABLE inheritance mapping strategies.
      *
-     * @psalm-param array<string, class-string> $map
+     * @param array<int|string, string> $map
      *
      * @return void
      */
@@ -3268,9 +3268,8 @@ public function setDiscriminatorMap(array $map)
     /**
      * Adds one entry of the discriminator map with a new class and corresponding name.
      *
-     * @param string $name
-     * @param string $className
-     * @psalm-param class-string $className
+     * @param int|string $name
+     * @param string     $className
      *
      * @return void
      *
@@ -3744,7 +3743,6 @@ public function getAssociationsByTargetClass($targetClass)
 
     /**
      * @param string|null $className
-     * @psalm-param string|class-string|null $className
      *
      * @return string|null null if the input value is null
      * @psalm-return class-string|null
diff --git a/lib/Doctrine/ORM/Mapping/DiscriminatorMap.php b/lib/Doctrine/ORM/Mapping/DiscriminatorMap.php
index 5e822daa613..ad36032b298 100644
--- a/lib/Doctrine/ORM/Mapping/DiscriminatorMap.php
+++ b/lib/Doctrine/ORM/Mapping/DiscriminatorMap.php
@@ -15,15 +15,11 @@
 #[Attribute(Attribute::TARGET_CLASS)]
 final class DiscriminatorMap implements Annotation
 {
-    /**
-     * @var array<string, string>
-     * @psalm-var array<string, class-string>
-     */
+    /** @var array<int|string, string> */
     public $value;
 
     /**
-     * @param array<string, string> $value
-     * @psalm-param array<string, class-string> $value
+     * @param array<int|string, string> $value
      */
     public function __construct(array $value)
     {
diff --git a/lib/Doctrine/ORM/Tools/Export/Driver/XmlExporter.php b/lib/Doctrine/ORM/Tools/Export/Driver/XmlExporter.php
index bfa07b532d0..95c74d1a877 100644
--- a/lib/Doctrine/ORM/Tools/Export/Driver/XmlExporter.php
+++ b/lib/Doctrine/ORM/Tools/Export/Driver/XmlExporter.php
@@ -82,7 +82,7 @@ public function exportClassMetadata(ClassMetadataInfo $metadata)
 
             foreach ($metadata->discriminatorMap as $value => $className) {
                 $discriminatorMappingXml = $discriminatorMapXml->addChild('discriminator-mapping');
-                $discriminatorMappingXml->addAttribute('value', $value);
+                $discriminatorMappingXml->addAttribute('value', (string) $value);
                 $discriminatorMappingXml->addAttribute('class', $className);
             }
         }
diff --git a/lib/Doctrine/ORM/Utility/IdentifierFlattener.php b/lib/Doctrine/ORM/Utility/IdentifierFlattener.php
index 837f2dc1d57..8df8eb9ca2f 100644
--- a/lib/Doctrine/ORM/Utility/IdentifierFlattener.php
+++ b/lib/Doctrine/ORM/Utility/IdentifierFlattener.php
@@ -11,7 +11,7 @@
 
 use function assert;
 use function implode;
-use function is_object;
+use function is_a;
 
 /**
  * The IdentifierFlattener utility now houses some of the identifier manipulation logic from unit of work, so that it
@@ -55,7 +55,7 @@ public function flattenIdentifier(ClassMetadata $class, array $id): array
         $flatId = [];
 
         foreach ($class->identifier as $field) {
-            if (isset($class->associationMappings[$field]) && isset($id[$field]) && is_object($id[$field])) {
+            if (isset($class->associationMappings[$field]) && isset($id[$field]) && is_a($id[$field], $class->associationMappings[$field]['targetEntity'])) {
                 $targetClassMetadata = $this->metadataFactory->getMetadataFor(
                     $class->associationMappings[$field]['targetEntity']
                 );
diff --git a/psalm-baseline.xml b/psalm-baseline.xml
index f0e56991cc8..ad0bb9a1798 100644
--- a/psalm-baseline.xml
+++ b/psalm-baseline.xml
@@ -495,8 +495,7 @@
     </PropertyNotSetInConstructor>
   </file>
   <file src="lib/Doctrine/ORM/Mapping/Builder/ClassMetadataBuilder.php">
-    <ArgumentTypeCoercion occurrences="2">
-      <code>$class</code>
+    <ArgumentTypeCoercion occurrences="1">
       <code>$repositoryClassName</code>
     </ArgumentTypeCoercion>
     <DeprecatedMethod occurrences="1">
@@ -871,8 +870,7 @@
     </MissingParamType>
   </file>
   <file src="lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php">
-    <ArgumentTypeCoercion occurrences="3">
-      <code>$map</code>
+    <ArgumentTypeCoercion occurrences="2">
       <code>(string) $xmlRoot['repository-class']</code>
       <code>isset($xmlRoot['repository-class']) ? (string) $xmlRoot['repository-class'] : null</code>
     </ArgumentTypeCoercion>
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/GH9335Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/GH9335Test.php
new file mode 100644
index 00000000000..cd1729902f7
--- /dev/null
+++ b/tests/Doctrine/Tests/ORM/Functional/Ticket/GH9335Test.php
@@ -0,0 +1,219 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\DBAL\ParameterType;
+use Doctrine\DBAL\Platforms\AbstractPlatform;
+use Doctrine\DBAL\Types\Type;
+use Doctrine\DBAL\Types\Type as DBALType;
+use Doctrine\ORM\Mapping\Column;
+use Doctrine\ORM\Mapping\Entity;
+use Doctrine\ORM\Mapping\Id;
+use Doctrine\ORM\Mapping\JoinColumn;
+use Doctrine\ORM\Mapping\OneToOne;
+use Doctrine\Tests\OrmFunctionalTestCase;
+
+/**
+ * @group GH9335
+ */
+final class GH9335Test extends OrmFunctionalTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        if (! DBALType::hasType(GH9335IntObjectType::class)) {
+            DBALType::addType(GH9335IntObjectType::class, GH9335IntObjectType::class);
+        }
+
+        $this->setUpEntitySchema([GH9335Book::class, GH9335Author::class]);
+    }
+
+    /**
+     *  Verifies that entities with foreign keys with custom id object types don't throw an exception
+     *
+     * The test passes when refresh() does not throw an exception
+     */
+    public function testFlattenIdentifierWithObjectId(): void
+    {
+        $author = new GH9335Author('Douglas Adams');
+        $book   = new GH9335Book(new GH9335IntObject(42), 'The Hitchhiker\'s Guide to the Galaxy', $author);
+
+        $this->_em->persist($author);
+        $this->_em->persist($book);
+        $this->_em->flush();
+
+        $this->_em->refresh($book);
+
+        self::assertInstanceOf(GH9335IntObject::class, $book->getId());
+    }
+}
+
+
+class GH9335IntObjectType extends Type
+{
+    public function getSQLDeclaration(array $column, AbstractPlatform $platform): string
+    {
+        return $platform->getIntegerTypeDeclarationSQL($column);
+    }
+
+    public function getName(): string
+    {
+        return self::class;
+    }
+
+    public function convertToDatabaseValue($value, AbstractPlatform $platform): int
+    {
+        return $value->wrappedInt;
+    }
+
+    public function convertToPHPValue($value, AbstractPlatform $platform): GH9335IntObject
+    {
+        return new GH9335IntObject((int) $value);
+    }
+
+    public function getBindingType(): int
+    {
+        return ParameterType::INTEGER;
+    }
+
+    public function requiresSQLCommentHint(AbstractPlatform $platform): bool
+    {
+        return true;
+    }
+}
+
+class GH9335IntObject
+{
+    /** @var int */
+    public $wrappedInt;
+
+    public function __construct(int $wrappedInt)
+    {
+        $this->wrappedInt = $wrappedInt;
+    }
+
+    public function __toString(): string
+    {
+        return (string) $this->wrappedInt;
+    }
+}
+
+/**
+ * @Entity
+ */
+class GH9335Book
+{
+    /**
+     * @var GH9335IntObject
+     * @Id
+     * @Column(type=GH9335IntObjectType::class, unique=true)
+     */
+    private $id;
+
+    /**
+     * @Column(type="string")
+     * @var string
+     */
+    private $title;
+
+
+    /**
+     * @OneToOne(targetEntity="GH9335Author", mappedBy="book", cascade={"persist", "remove"})
+     * @var GH9335Author
+     */
+    private $author;
+
+    public function __construct(GH9335IntObject $id, string $title, ?GH9335Author $author = null)
+    {
+        $this->setId($id);
+        $this->setTitle($title);
+        $this->setAuthor($author);
+    }
+
+    public function getId(): ?GH9335IntObject
+    {
+        return $this->id;
+    }
+
+    public function setId($id): void
+    {
+        $this->id = $id;
+    }
+
+    public function getTitle(): ?string
+    {
+        return $this->title;
+    }
+
+    public function setTitle($title): void
+    {
+        $this->title = $title;
+    }
+
+    public function getAuthor(): ?GH9335Author
+    {
+        return $this->author;
+    }
+
+    public function setAuthor(?GH9335Author $author): self
+    {
+        $this->author = $author;
+
+        // set the owning side of the relation
+        if ($author) {
+            $author->setBook($this);
+        }
+
+        return $this;
+    }
+}
+
+/**
+ * @Entity
+ */
+class GH9335Author
+{
+    /**
+     * @var GH9335Book
+     * @Id
+     * @OneToOne(targetEntity="GH9335Book", inversedBy="author")
+     * @JoinColumn(name="book")
+     */
+    private $book;
+
+    /**
+     * @Column(type="string", nullable="true" )
+     * @var string
+     */
+    private $name;
+
+    public function __construct(?string $name)
+    {
+        $this->setName($name);
+    }
+
+    public function getBook(): ?GH9335Book
+    {
+        return $this->book;
+    }
+
+    public function setBook(GH9335Book $book): self
+    {
+        $this->book = $book;
+
+        return $this;
+    }
+
+    public function getName(): string
+    {
+        return $this->name;
+    }
+
+    public function setName(string $name): void
+    {
+        $this->name = $name;
+    }
+}
diff --git a/tests/Doctrine/Tests/ORM/Query/LanguageRecognitionTest.php b/tests/Doctrine/Tests/ORM/Query/LanguageRecognitionTest.php
index 1a691504431..a7d8617ae41 100644
--- a/tests/Doctrine/Tests/ORM/Query/LanguageRecognitionTest.php
+++ b/tests/Doctrine/Tests/ORM/Query/LanguageRecognitionTest.php
@@ -16,8 +16,6 @@
 use Doctrine\Tests\Mocks\NullSqlWalker;
 use Doctrine\Tests\OrmTestCase;
 
-use const PHP_EOL;
-
 class LanguageRecognitionTest extends OrmTestCase
 {
     /** @var EntityManagerInterface */
@@ -28,34 +26,16 @@ protected function setUp(): void
         $this->entityManager = $this->getTestEntityManager();
     }
 
-    public function assertValidDQL($dql, $debug = false): void
+    public function assertValidDQL(string $dql): void
     {
-        try {
-            $parserResult = $this->parseDql($dql);
-            $this->addToAssertionCount(1);
-        } catch (QueryException $e) {
-            if ($debug) {
-                echo $e->getTraceAsString() . PHP_EOL;
-            }
-
-            self::fail($e->getMessage());
-        }
+        $this->parseDql($dql);
+        $this->addToAssertionCount(1);
     }
 
-    public function assertInvalidDQL($dql, $debug = false): void
+    public function assertInvalidDQL(string $dql): void
     {
-        try {
-            $parserResult = $this->parseDql($dql);
-
-            self::fail('No syntax errors were detected, when syntax errors were expected');
-        } catch (QueryException $e) {
-            if ($debug) {
-                echo $e->getMessage() . PHP_EOL;
-                echo $e->getTraceAsString() . PHP_EOL;
-            }
-
-            $this->addToAssertionCount(1);
-        }
+        $this->expectException(QueryException::class);
+        $this->parseDql($dql);
     }
 
     /**
@@ -370,7 +350,7 @@ public function testSelectLiteralInSubselect(): void
      */
     public function testConstantValueInSelect(): void
     {
-        $this->assertValidDQL("SELECT u.name, 'foo' AS bar FROM Doctrine\Tests\Models\CMS\CmsUser u", true);
+        $this->assertValidDQL("SELECT u.name, 'foo' AS bar FROM Doctrine\Tests\Models\CMS\CmsUser u");
     }
 
     public function testDuplicateAliasInSubselectPart(): void
@@ -594,7 +574,7 @@ public function testCustomFunctionsReturningStringInStringPrimary(): void
     {
         $this->entityManager->getConfiguration()->addCustomStringFunction('CC', Query\AST\Functions\ConcatFunction::class);
 
-        $this->assertValidDQL("SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE CC('%', u.name) LIKE '%foo%'", true);
+        $this->assertValidDQL("SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE CC('%', u.name) LIKE '%foo%'");
     }
 
     /**