diff --git a/src/wp-includes/class-wp-image-editor-imagick.php b/src/wp-includes/class-wp-image-editor-imagick.php
index 57ed7c79e56ae..63b7b5d397f85 100644
--- a/src/wp-includes/class-wp-image-editor-imagick.php
+++ b/src/wp-includes/class-wp-image-editor-imagick.php
@@ -1085,6 +1085,8 @@ public function save( $destfilename = null, $mime_type = null ) {
 	 * Removes PDF alpha after it's been read.
 	 *
 	 * @since 6.4.0
+	 *
+	 * @return void|WP_Error WP_Error object if the alpha channel could not be removed.
 	 */
 	protected function remove_pdf_alpha_channel() {
 		$version = Imagick::getVersion();