diff --git a/wp-admin/includes/ajax-actions.php b/wp-admin/includes/ajax-actions.php
index e132ac8..58f797e 100644
--- a/wp-admin/includes/ajax-actions.php
+++ b/wp-admin/includes/ajax-actions.php
@@ -3477,7 +3477,7 @@ function wp_ajax_update_theme() {
 		) );
 	}
 
-	$stylesheet = preg_replace( '/[^A-z0-9_\-]/', '', wp_unslash( $_POST['slug'] ) );
+	$stylesheet = preg_replace( '|[^A-z0-9_/\-]|', '', $_POST['slug'] );
 	$status     = array(
 		'update'     => 'theme',
 		'slug'       => $stylesheet,
@@ -3562,7 +3562,7 @@ function wp_ajax_delete_theme() {
 		) );
 	}
 
-	$stylesheet = preg_replace( '/[^A-z0-9_\-]/', '', wp_unslash( $_POST['slug'] ) );
+	$stylesheet = preg_replace( '|[^A-z0-9_/\-]|', '', $_POST['slug'] );
 	$status     = array(
 		'delete' => 'theme',
 		'slug'   => $stylesheet,