diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index ca30890169..0bf6c52654 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -6327,12 +6327,12 @@ function is_local_attachment( $url ) {
  *
  * @param string|array $args             Arguments for inserting an attachment.
  * @param string|false $file             Optional. Filename.
- * @param int          $parent_post      Optional. Parent post ID.
+ * @param int          $parent_post_id   Optional. Parent post ID.
  * @param bool         $wp_error         Optional. Whether to return a WP_Error on failure. Default false.
  * @param bool         $fire_after_hooks Optional. Whether to fire the after insert hooks. Default true.
  * @return int|WP_Error The attachment ID on success. The value 0 or WP_Error on failure.
  */
-function wp_insert_attachment( $args, $file = false, $parent_post = 0, $wp_error = false, $fire_after_hooks = true ) {
+function wp_insert_attachment( $args, $file = false, $parent_post_id = 0, $wp_error = false, $fire_after_hooks = true ) {
 	$defaults = array(
 		'file'        => $file,
 		'post_parent' => 0,
@@ -6340,8 +6340,8 @@ function wp_insert_attachment( $args, $file = false, $parent_post = 0, $wp_error
 
 	$data = wp_parse_args( $args, $defaults );
 
-	if ( ! empty( $parent_post ) ) {
-		$data['post_parent'] = $parent_post;
+	if ( ! empty( $parent_post_id ) ) {
+		$data['post_parent'] = $parent_post_id;
 	}
 
 	$data['post_type'] = 'attachment';
diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php
index 210505c862..61fd9233e3 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php
@@ -134,21 +134,21 @@ class WP_REST_Revisions_Controller extends WP_REST_Controller {
 	 *
 	 * @since 4.7.2
 	 *
-	 * @param int $parent_post Supplied ID.
+	 * @param int $parent_post_id Supplied ID.
 	 * @return WP_Post|WP_Error Post object if ID is valid, WP_Error otherwise.
 	 */
-	protected function get_parent( $parent_post ) {
+	protected function get_parent( $parent_post_id ) {
 		$error = new WP_Error(
 			'rest_post_invalid_parent',
 			__( 'Invalid post parent ID.' ),
 			array( 'status' => 404 )
 		);
 
-		if ( (int) $parent_post <= 0 ) {
+		if ( (int) $parent_post_id <= 0 ) {
 			return $error;
 		}
 
-		$parent_post = get_post( (int) $parent_post );
+		$parent_post = get_post( (int) $parent_post_id );
 
 		if ( empty( $parent_post ) || empty( $parent_post->ID )
 			|| $this->parent_post_type !== $parent_post->post_type
diff --git a/tests/phpunit/includes/factory/class-wp-unittest-factory-for-attachment.php b/tests/phpunit/includes/factory/class-wp-unittest-factory-for-attachment.php
index 85206d5159..262c6c4640 100644
--- a/tests/phpunit/includes/factory/class-wp-unittest-factory-for-attachment.php
+++ b/tests/phpunit/includes/factory/class-wp-unittest-factory-for-attachment.php
@@ -55,12 +55,12 @@ class WP_UnitTest_Factory_For_Attachment extends WP_UnitTest_Factory_For_Post {
 	 * @since 4.4.0
 	 * @since 6.2.0 Returns a WP_Error object on failure.
 	 *
-	 * @param string $file   The file name to create attachment object for.
-	 * @param int    $parent ID of the post to attach the file to.
+	 * @param string $file           The file name to create attachment object for.
+	 * @param int    $parent_post_id ID of the post to attach the file to.
 	 *
 	 * @return int|WP_Error The attachment ID on success, WP_Error object on failure.
 	 */
-	public function create_upload_object( $file, $parent = 0 ) {
+	public function create_upload_object( $file, $parent_post_id = 0 ) {
 		$contents = file_get_contents( $file );
 		$upload   = wp_upload_bits( wp_basename( $file ), null, $contents );
 
@@ -78,13 +78,13 @@ class WP_UnitTest_Factory_For_Attachment extends WP_UnitTest_Factory_For_Post {
 			'post_title'     => wp_basename( $upload['file'] ),
 			'post_content'   => '',
 			'post_type'      => 'attachment',
-			'post_parent'    => $parent,
+			'post_parent'    => $parent_post_id,
 			'post_mime_type' => $type,
 			'guid'           => $upload['url'],
 		);
 
 		// Save the data.
-		$attachment_id = wp_insert_attachment( $attachment, $upload['file'], $parent, true );
+		$attachment_id = wp_insert_attachment( $attachment, $upload['file'], $parent_post_id, true );
 
 		if ( is_wp_error( $attachment_id ) ) {
 			return $attachment_id;