diff --git a/utils/make-phar.php b/utils/make-phar.php
index 186f5638c..80af3d201 100644
--- a/utils/make-phar.php
+++ b/utils/make-phar.php
@@ -238,6 +238,7 @@ function get_composer_versions( $current_version ) {
 		->in( WP_CLI_VENDOR_DIR . '/gettext' )
 		->in( WP_CLI_VENDOR_DIR . '/mck89' )
 		->exclude( 'demo' )
+		->exclude( 'wp-cli-tests' )
 		->exclude( 'nb/oxymel/OxymelTest.php' )
 		->exclude( 'composer/spdx-licenses' )
 		->exclude( 'composer/composer/src/Composer/Command' )