diff --git a/src/WP_CLI/Core/CoreUpgrader.php b/src/WP_CLI/Core/CoreUpgrader.php
index ec415ab56..9784552b5 100644
--- a/src/WP_CLI/Core/CoreUpgrader.php
+++ b/src/WP_CLI/Core/CoreUpgrader.php
@@ -22,11 +22,12 @@ class CoreUpgrader extends DefaultCoreUpgrader {
 	 *
 	 * @access public
 	 *
-	 * @param string $package The URI of the package. If this is the full path to an
-	 *                        existing local file, it will be returned untouched.
+	 * @param string $package          The URI of the package. If this is the full path to an
+	 *                                 existing local file, it will be returned untouched.
+	 * @param bool   $check_signatures Whether to validate file signatures. Default true.
 	 * @return string|WP_Error The full path to the downloaded package file, or a WP_Error object.
 	 */
-	public function download_package( $package ) {
+	public function download_package( $package, $check_signatures = true ) {
 
 		/**
 		 * Filter whether to return the package.