diff --git a/Changes b/Changes
index 9ff7957..54bc3e1 100644
--- a/Changes
+++ b/Changes
@@ -1,6 +1,9 @@
 Revision history for Perl extension Params::CallbackRequest.
 
 1.16
+      - Fixed bug detecting mod_perl2. Reported by Jimmy Li.
+      - Fixed a bug in the redirect() method under mod_perl2. Report and fix
+        from Jimmy Li.
 
 1.15  2006-05-26T21:28:55
       - Added the 'requester' attribute to Params::Callback. This can be
diff --git a/lib/Params/Callback.pm b/lib/Params/Callback.pm
index e9d9407..f44bdae 100644
--- a/lib/Params/Callback.pm
+++ b/lib/Params/Callback.pm
@@ -17,12 +17,12 @@ Params::Validate::validation_options
 
 my $is_num = { 'valid priority' => sub { $_[0] =~ /^\d$/ } };
 
-# Use Apache::RequestRec for mod_perl 2
-my $ap_req_class = defined $mod_perl::VERSION && $mod_perl::VERSION >= 1.99
-    ? 'Apache::RequestRec'
-    : defined $mod_perl2::VERSION
+# Use Apache2?::RequestRec for mod_perl 2
+use constant APREQ_CLASS => exists $ENV{MOD_PERL_API_VERSION}
+    ? $ENV{MOD_PERL_API_VERSION} >= 2
         ? 'Apache2::RequestRec'
-        : 'Apache';
+        : 'Apache::RequestRec'
+    : 'Apache';
 
 BEGIN {
     # The object-oriented interface is only supported with the use of
@@ -59,7 +59,7 @@ my %valid_params = (
     },
 
     apache_req => {
-        isa      => $ap_req_class,
+        isa      => APREQ_CLASS,
         optional => 1,
     },
 
@@ -354,7 +354,7 @@ sub redirect {
     if (my $r = $self->apache_req) {
         $r->method('GET');
         $r->headers_in->unset('Content-length');
-        $r->err_header_out( Location => $url );
+        $r->err_headers_out->add( Location => $url );
     }
     $self->abort($status) unless $wait;
 }
diff --git a/t/08apache.t b/t/08apache.t
index d821ab4..6c87ced 100644
--- a/t/08apache.t
+++ b/t/08apache.t
@@ -1,6 +1,6 @@
 #!perl -w
 
-# $Id: 08apache.t,v 1.2 2003/08/19 17:39:08 david Exp $
+# $Id$
 
 use strict;
 use Test::More;
@@ -10,7 +10,7 @@ my $cbs = [];
 BEGIN {
     plan skip_all => 'Testing of apache_req requires Apache::FakeRequest'
       unless eval { require Apache::FakeRequest };
-    plan tests => 14;
+    plan tests => 15;
     use_ok('Params::CallbackRequest');
 }
 
@@ -21,6 +21,10 @@ BEGIN {
 package Params::Callback::Test::Headers;
 sub unset {}
 sub new { bless {} }
+sub add {
+    my ($self, $key, $val) = @_;
+    $self->{$key} = $val;
+}
 
 package main;
 
@@ -51,15 +55,20 @@ push @$cbs, { pkg_key => $key,
 
 ##############################################################################
 # Create the callback request object.
-ok( my $cb_request = Params::CallbackRequest->new( callbacks => $cbs),
+ok( my $cb_request = Params::CallbackRequest->new( callbacks => $cbs ),
     "Construct CBExec object" );
 isa_ok($cb_request, 'Params::CallbackRequest' );
 
 # Create an Apache request object.
-ok( my $headers = Params::Callback::Test::Headers->new,
-     "Create headers object" );
-
-ok( my $apache_req = Apache::FakeRequest->new( headers_in => $headers ),
+ok( my $headers_in = Params::Callback::Test::Headers->new,
+     "Create headers_in object" );
+ok( my $err_headers_out = Params::Callback::Test::Headers->new,
+     "Create err_headers_out object" );
+
+ok( my $apache_req = Apache::FakeRequest->new(
+    headers_in      => $headers_in,
+    err_headers_out => $err_headers_out,
+),
     "Create apache request object" );
 
 # Execute the delayed redirection callback.
@@ -68,9 +77,10 @@ my %params = ( "$key|redir_cb"    => 1,
 is( $cb_request->request(\%params, apache_req => $apache_req), 302,
     "Execute delayed redir callback" );
 
-# Check apache request values (too bad Apache::FakeRequest can't handle
-# parameter lists. This should be good enough, though.
-is( delete $apache_req->{err_header_out}, 'Location', "Check err_header_out" );
+# Check apache request values.
+is_deeply $apache_req->{err_headers_out}, { Location => $url },
+    "Check err_header_out";
+delete $apache_req->{err_headers_out}{Location};
 is( delete $apache_req->{method}, 'GET', "Check request method" );
 
 ##############################################################################
@@ -80,7 +90,9 @@ is( $cb_request->request(\%params, apache_req => $apache_req), 302,
     "Execute instant redir callback" );
 
 # Check the Apache settings again.
-is( delete $apache_req->{err_header_out}, 'Location', "Check err_header_out" );
+is_deeply $apache_req->{err_headers_out}, { Location => $url },
+    "Check err_header_out";
+delete $apache_req->{err_headers_out}{Location};
 is( delete $apache_req->{method}, 'GET', "Check request method" );
 
 ##############################################################################