diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
index 872a6607cb..40955b3c1d 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
@@ -77,18 +77,22 @@ class WP_REST_Posts_Controller extends WP_REST_Controller {
 			'schema' => array( $this, 'get_public_item_schema' ),
 		) );
 
+		$schema = $this->get_item_schema();
+		$get_item_args = array(
+			'context'  => $this->get_context_param( array( 'default' => 'view' ) ),
+		);
+		if ( isset( $schema['properties']['password'] ) ) {
+			$get_item_args['password'] = array(
+				'description' => __( 'The password for the post if it is password protected.' ),
+				'type'        => 'string',
+			);
+		}
 		register_rest_route( $this->namespace, '/' . $this->rest_base . '/(?P<id>[\d]+)', array(
 			array(
 				'methods'             => WP_REST_Server::READABLE,
 				'callback'            => array( $this, 'get_item' ),
 				'permission_callback' => array( $this, 'get_item_permissions_check' ),
-				'args'                => array(
-					'context'  => $this->get_context_param( array( 'default' => 'view' ) ),
-					'password' => array(
-						'description' => __( 'The password for the post if it is password protected.' ),
-						'type'        => 'string',
-					),
-				),
+				'args'                => $get_item_args,
 			),
 			array(
 				'methods'             => WP_REST_Server::EDITABLE,
diff --git a/tests/phpunit/tests/rest-api/rest-attachments-controller.php b/tests/phpunit/tests/rest-api/rest-attachments-controller.php
index 0de092dafc..a651a7622f 100644
--- a/tests/phpunit/tests/rest-api/rest-attachments-controller.php
+++ b/tests/phpunit/tests/rest-api/rest-attachments-controller.php
@@ -172,6 +172,19 @@ class WP_Test_REST_Attachments_Controller extends WP_Test_REST_Post_Type_Control
 		$this->assertEqualSets( $media_types, $data['endpoints'][0]['args']['media_type']['enum'] );
 	}
 
+	public function test_registered_get_item_params() {
+		$id1 = $this->factory->attachment->create_object( $this->test_file, 0, array(
+			'post_mime_type' => 'image/jpeg',
+			'post_excerpt'   => 'A sample caption',
+		) );
+		$request = new WP_REST_Request( 'OPTIONS', sprintf( '/wp/v2/media/%d', $id1 ) );
+		$response = $this->server->dispatch( $request );
+		$data = $response->get_data();
+		$keys = array_keys( $data['endpoints'][0]['args'] );
+		sort( $keys );
+		$this->assertEquals( array( 'context' ), $keys );
+	}
+
 	public function test_get_items() {
 		wp_set_current_user( 0 );
 		$id1 = $this->factory->attachment->create_object( $this->test_file, 0, array(
diff --git a/tests/phpunit/tests/rest-api/rest-posts-controller.php b/tests/phpunit/tests/rest-api/rest-posts-controller.php
index 886ae3c5a6..7389b971b3 100644
--- a/tests/phpunit/tests/rest-api/rest-posts-controller.php
+++ b/tests/phpunit/tests/rest-api/rest-posts-controller.php
@@ -121,6 +121,15 @@ class WP_Test_REST_Posts_Controller extends WP_Test_REST_Post_Type_Controller_Te
 			), $keys );
 	}
 
+	public function test_registered_get_item_params() {
+		$request = new WP_REST_Request( 'OPTIONS', sprintf( '/wp/v2/posts/%d', self::$post_id ) );
+		$response = $this->server->dispatch( $request );
+		$data = $response->get_data();
+		$keys = array_keys( $data['endpoints'][0]['args'] );
+		sort( $keys );
+		$this->assertEquals( array( 'context', 'password' ), $keys );
+	}
+
 	public function test_get_items() {
 		$request = new WP_REST_Request( 'GET', '/wp/v2/posts' );
 		$response = $this->server->dispatch( $request );