diff --git a/src/FlatMapper.php b/src/FlatMapper.php
index 9bd3043..e8a3c61 100644
--- a/src/FlatMapper.php
+++ b/src/FlatMapper.php
@@ -25,7 +25,7 @@ class FlatMapper
 
     // TODO for now those are unused
     private ?CacheInterface $cacheService = null; // @phpstan-ignore-line
-    private bool $validateMapping = true; // @phpstan-ignore-line
+    private bool $validateMapping = true;
 
     public function setCacheService(CacheInterface $cacheService): void
     {
@@ -57,7 +57,8 @@ private function createMappingRecursive(string $dtoClassName, string $rootDtoCla
 
         $reflectionClass = new ReflectionClass($dtoClassName);
 
-        foreach ($reflectionClass->getProperties() as $reflectionProperty) {
+        $identifiersCount = 0;
+        foreach ($reflectionClass->getConstructor()->getParameters() as $reflectionProperty) {
             $propertyName = $reflectionProperty->getName();
             $isIdentifier = false;
             foreach ($reflectionProperty->getAttributes() as $attribute) {
@@ -65,18 +66,13 @@ private function createMappingRecursive(string $dtoClassName, string $rootDtoCla
                     $this->objectsMapping[$rootDtoClassName][$dtoClassName][$propertyName] = (string)$attribute->getArguments()[0];
                     $this->createMappingRecursive($attribute->getArguments()[0], $rootDtoClassName);
                     continue 2;
-                }
-
-                if ($attribute->getName() === ColumnArray::class) {
+                } else if ($attribute->getName() === ColumnArray::class) {
                     $this->objectsMapping[$rootDtoClassName][$dtoClassName][$propertyName] = (string)$attribute->getArguments()[0];
                     continue 2;
-                }
-
-                if ($attribute->getName() === Identifier::class) {
+                } else if ($attribute->getName() === Identifier::class) {
+                    $identifiersCount++;
                     $isIdentifier = true;
-                }
-
-                if ($attribute->getName() === InboundPropertyName::class) {
+                } else if ($attribute->getName() === InboundPropertyName::class) {
                     $propertyName = $attribute->getArguments()[0];
                 }
             }
@@ -88,8 +84,14 @@ private function createMappingRecursive(string $dtoClassName, string $rootDtoCla
             $this->objectsMapping[$rootDtoClassName][$dtoClassName][$propertyName] = null;
         }
 
-        if (count($this->objectIdentifiers[$rootDtoClassName]) !== count(array_unique($this->objectIdentifiers[$rootDtoClassName]))) {
-            throw new RuntimeException('Several data identifiers are identical: ' . print_r($this->objectIdentifiers[$rootDtoClassName], true));
+        if($this->validateMapping) {
+            if($identifiersCount !== 1) {
+                throw new RuntimeException($dtoClassName.' contains more than one #[Identifier] attribute.');
+            }
+
+            if (count($this->objectIdentifiers[$rootDtoClassName]) !== count(array_unique($this->objectIdentifiers[$rootDtoClassName]))) {
+                throw new RuntimeException('Several data identifiers are identical: ' . print_r($this->objectIdentifiers[$rootDtoClassName], true));
+            }
         }
     }
 
diff --git a/tests/Examples/Invalid/RootDTOWithTooManyIdentifiers.php b/tests/Examples/Invalid/RootDTOWithTooManyIdentifiers.php
new file mode 100644
index 0000000..3ca3adf
--- /dev/null
+++ b/tests/Examples/Invalid/RootDTOWithTooManyIdentifiers.php
@@ -0,0 +1,26 @@
+<?php
+declare(strict_types=1);
+
+namespace Pixelshaped\FlatMapperBundle\Tests\Examples\Invalid;
+
+use Pixelshaped\FlatMapperBundle\Attributes\Identifier;
+use Pixelshaped\FlatMapperBundle\Attributes\InboundPropertyName;
+use Pixelshaped\FlatMapperBundle\Attributes\ReferencesArray;
+use Pixelshaped\FlatMapperBundle\Tests\Examples\Invalid\LeafDTO;
+
+class RootDTOWithTooManyIdentifiers
+{
+    /**
+     * @param array<LeafDTO> $leafs
+     */
+    public function __construct(
+        #[Identifier]
+        #[InboundPropertyName('object1_id')]
+        public int $id,
+        #[Identifier]
+        #[InboundPropertyName('object1_name')]
+        public string $name,
+        #[ReferencesArray(LeafDTO::class)]
+        public array $leafs,
+    ) {}
+}
diff --git a/tests/FlatMapperTest.php b/tests/FlatMapperTest.php
index c375012..123984d 100644
--- a/tests/FlatMapperTest.php
+++ b/tests/FlatMapperTest.php
@@ -6,6 +6,7 @@
 use PHPUnit\Framework\Attributes\CoversMethod;
 use PHPUnit\Framework\TestCase;
 use Pixelshaped\FlatMapperBundle\FlatMapper;
+use Pixelshaped\FlatMapperBundle\Tests\Examples\Invalid\RootDTOWithTooManyIdentifiers;
 use Pixelshaped\FlatMapperBundle\Tests\Examples\Valid\ColumnArrayDTO;
 use Pixelshaped\FlatMapperBundle\Tests\Examples\Valid\LeafDTO;
 use Pixelshaped\FlatMapperBundle\Tests\Examples\Valid\RootDTO as ValidRootDTO;
@@ -24,7 +25,7 @@ public function testCreateMappingWithValidDTOsDoesNotAssert(): void
         $mapper->createMapping(ValidRootDTO::class);
     }
 
-    public function testCreateMappingWithInvalidDTOsAsserts(): void
+    public function testCreateMappingWithSeveralIdenticalIdentifiersAsserts(): void
     {
         $this->expectException(RuntimeException::class);
         $this->expectExceptionMessageMatches("/Several data identifiers are identical/");
@@ -32,6 +33,14 @@ public function testCreateMappingWithInvalidDTOsAsserts(): void
         $mapper->createMapping(InvalidRootDTO::class);
     }
 
+    public function testCreateMappingWithTooManyIdentifiersAsserts(): void
+    {
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessageMatches("/contains more than one #\[Identifier\] attribute/");
+        $mapper = new FlatMapper();
+        $mapper->createMapping(RootDTOWithTooManyIdentifiers::class);
+    }
+
     public function testMapValidNestedDTOs(): void
     {
         $results = [