diff --git a/src/Construction/DoctrineObjectConstructor.php b/src/Construction/DoctrineObjectConstructor.php
index 9a64e6305..e27064903 100644
--- a/src/Construction/DoctrineObjectConstructor.php
+++ b/src/Construction/DoctrineObjectConstructor.php
@@ -107,11 +107,19 @@ public function construct(DeserializationVisitorInterface $visitor, ClassMetadat
                 return $this->fallbackConstructor->construct($visitor, $metadata, $data, $type, $context);
             }
 
+            $identifierValue = null;
             if (is_object($data) && 'SimpleXMLElement' === get_class($data)) {
-                $identifierList[$name] = (string) $data->{$propertyMetadata->serializedName};
+                $identifierValue = (string) $data->{$propertyMetadata->serializedName};
             } else {
-                $identifierList[$name] = $data[$propertyMetadata->serializedName];
+                $identifierValue = $data[$propertyMetadata->serializedName];
             }
+
+            if (null === $identifierValue) {
+                // Doctrine doesn't support null values in identifier values.
+                return $this->fallbackConstructor->construct($visitor, $metadata, $data, $type, $context);
+            }
+
+            $identifierList[$name] = $identifierValue;
         }
 
         if (empty($identifierList)) {
diff --git a/tests/Serializer/Doctrine/ObjectConstructorTest.php b/tests/Serializer/Doctrine/ObjectConstructorTest.php
index 9ace32a94..31b99ad1e 100644
--- a/tests/Serializer/Doctrine/ObjectConstructorTest.php
+++ b/tests/Serializer/Doctrine/ObjectConstructorTest.php
@@ -86,6 +86,21 @@ public function testFindEntity()
         self::assertEquals($author, $authorFetched);
     }
 
+    public function testFindEntityNullIdentifierUsesFallback()
+    {
+        $author = new Author('John');
+        $fallback = $this->getMockBuilder(ObjectConstructorInterface::class)->getMock();
+        $fallback->expects($this->once())->method('construct')->willReturn($author);
+
+        $type = ['name' => Author::class, 'params' => []];
+        $class = $this->driver->loadMetadataForClass(new \ReflectionClass(Author::class));
+
+        $constructor = new DoctrineObjectConstructor($this->registry, $fallback);
+        $authorFetched = $constructor->construct($this->visitor, $class, ['id' => null], $type, $this->context);
+
+        self::assertEquals($author, $authorFetched);
+    }
+
     public function testFindEntityExcludedByGroupsUsesFallback()
     {
         $graph = $this->createMock(GraphNavigatorInterface::class);