diff --git a/wp-includes/ms-default-filters.php b/wp-includes/ms-default-filters.php
index d0054b502e..042751e491 100644
--- a/wp-includes/ms-default-filters.php
+++ b/wp-includes/ms-default-filters.php
@@ -31,6 +31,7 @@ add_action( 'network_site_new_created_user', 'wp_send_new_user_notifications' );
 add_action( 'network_site_users_created_user', 'wp_send_new_user_notifications' );
 add_action( 'network_user_new_created_user', 'wp_send_new_user_notifications' );
 add_filter( 'sanitize_user', 'strtolower' );
+add_action( 'deleted_user', 'wp_delete_signup_on_user_delete', 10, 3 );
 
 // Roles.
 add_action( 'switch_blog', 'wp_switch_roles_and_user', 1, 2 );
diff --git a/wp-includes/ms-functions.php b/wp-includes/ms-functions.php
index c2af99ef55..9707818787 100644
--- a/wp-includes/ms-functions.php
+++ b/wp-includes/ms-functions.php
@@ -1276,6 +1276,21 @@ function wpmu_activate_signup( $key ) {
 	);
 }
 
+/**
+ * Deletes am associated signup entry when a user is deleted from the database.
+ *
+ * @since 5.5.0
+ *
+ * @param int      $id       ID of the user to delete.
+ * @param int|null $reassign ID of the user to reassign posts and links to.
+ * @param WP_User  $user     User object.
+ */
+function wp_delete_signup_on_user_delete( $id, $reassign, $user ) {
+	global $wpdb;
+
+	$wpdb->delete( $wpdb->signups, array( 'user_login' => $user->user_login ) );
+}
+
 /**
  * Create a user.
  *
diff --git a/wp-includes/version.php b/wp-includes/version.php
index b2243ec6d2..d5ab5b3b9c 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-48314';
+$wp_version = '5.5-alpha-48315';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.