--- /dev/null
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More tests => 2;
+
+BEGIN {
+ use_ok('Class::C3');
+}
+
+=pod
+
+rt.cpan.org # 21558
+
+If compile-time code from another module issues a [re]initialize() part-way
+through the process of setting up own our modules, that shouldn't prevent
+our own initialize() call from working properly.
+
+=cut
+
+{
+ package TestMRO::A;
+ use Class::C3;
+ sub testmethod { 42 }
+
+ package TestMRO::B;
+ use base 'TestMRO::A';
+ use Class::C3;
+
+ package TestMRO::C;
+ use base 'TestMRO::A';
+ use Class::C3;
+ sub testmethod { shift->next::method + 1 }
+
+ package TestMRO::D;
+ BEGIN { Class::C3::initialize }
+ use base 'TestMRO::B';
+ use base 'TestMRO::C';
+ use Class::C3;
+ sub new {
+ my $class = shift;
+ my $self = {};
+ bless $self => $class;
+ }
+}
+
+Class::C3::initialize;
+is(TestMRO::D->new->testmethod, 43, 'double-initialize works ok');