diff --git a/src/Model/Schema/Discriminator.php b/src/Model/Schema/Discriminator.php
index 0778e5e..9182c8f 100644
--- a/src/Model/Schema/Discriminator.php
+++ b/src/Model/Schema/Discriminator.php
@@ -6,9 +6,13 @@
 
 final readonly class Discriminator
 {
-    /** @param array<string, string> $mapping */
+    /**
+     * @param  array<string, string>  $mapping
+     * @param  array<string, mixed>  $extensions
+     */
     public function __construct(
         public string $propertyName,
         public array $mapping = [],
+        public array $extensions = [],
     ) {}
 }
diff --git a/src/Parser/Schema/Reader.php b/src/Parser/Schema/Reader.php
index c10014f..70ba9bc 100644
--- a/src/Parser/Schema/Reader.php
+++ b/src/Parser/Schema/Reader.php
@@ -263,6 +263,10 @@ private function discriminator(array $data): ?Discriminator
             $mapping[(string) $name] = $reference;
         }
 
-        return new Discriminator(Value::requiredString($value, 'propertyName', 'schema/discriminator'), $mapping);
+        return new Discriminator(
+            Value::requiredString($value, 'propertyName', 'schema/discriminator'),
+            $mapping,
+            Value::extensions($value),
+        );
     }
 }
diff --git a/tests/Schema/ReaderTest.php b/tests/Schema/ReaderTest.php
index 5d206ef..228edda 100644
--- a/tests/Schema/ReaderTest.php
+++ b/tests/Schema/ReaderTest.php
@@ -115,6 +115,52 @@ public function test_discriminator_is_read_from_both_the_string_and_object_forms
         self::assertSame(['cat' => '#/components/schemas/Cat'], $fromObject->discriminator?->mapping);
     }
 
+    public function test_discriminator_captures_extensions(): void
+    {
+        $reader = $this->reader(Version::V3_0);
+
+        $schema = $reader->read([
+            'oneOf' => [],
+            'discriminator' => [
+                'propertyName' => 'type',
+                'mapping' => ['string' => '#/components/schemas/Text'],
+                'x-mapping' => [
+                    '#/components/schemas/Email' => ['type' => 'string', 'format' => 'email'],
+                    '#/components/schemas/Text' => ['type' => 'string'],
+                ],
+                'x-propertyNames' => ['type', 'format'],
+            ],
+        ], '#/x');
+
+        self::assertInstanceOf(CompositeSchema::class, $schema);
+        self::assertSame([
+            'x-mapping' => [
+                '#/components/schemas/Email' => ['type' => 'string', 'format' => 'email'],
+                '#/components/schemas/Text' => ['type' => 'string'],
+            ],
+            'x-propertyNames' => ['type', 'format'],
+        ], $schema->discriminator?->extensions);
+
+        self::assertSame('type', $schema->discriminator?->propertyName);
+        self::assertSame(['string' => '#/components/schemas/Text'], $schema->discriminator?->mapping);
+    }
+
+    public function test_discriminator_extensions_default_to_empty(): void
+    {
+        $reader = $this->reader(Version::V3_0);
+
+        $fromString = $reader->read(['oneOf' => [], 'discriminator' => 'kind'], '#/x');
+        self::assertInstanceOf(CompositeSchema::class, $fromString);
+        self::assertSame([], $fromString->discriminator?->extensions);
+
+        $fromObject = $reader->read([
+            'oneOf' => [],
+            'discriminator' => ['propertyName' => 'kind'],
+        ], '#/x');
+        self::assertInstanceOf(CompositeSchema::class, $fromObject);
+        self::assertSame([], $fromObject->discriminator?->extensions);
+    }
+
     public function test_object_and_array_types_are_implied_from_their_keywords(): void
     {
         $reader = $this->reader(Version::V3_0);