diff --git a/lib/Pingback.pm b/lib/Pingback.pm
index 6d8c15de..e40607f9 100644
--- a/lib/Pingback.pm
+++ b/lib/Pingback.pm
@@ -307,10 +307,31 @@ sub _generate_identifier {
    my $dbh      = $instance->{dbh};
    my $dsn      = $instance->{dsn};
 
-   my $sql    = q{SELECT CONCAT(@@hostname, @@port)};
+   # MySQL 5.1+ has @@hostname and @@port
+   # MySQL 5.0  has @@hostname but port only in SHOW VARS
+   # MySQL 4.x  has nothing, so we use the dsn
+   my $sql = q{SELECT CONCAT(@@hostname, @@port)};
+   PTDEBUG && _d($sql);
    my ($name) = eval { $dbh->selectrow_array($sql) };
-   if ( $EVAL_ERROR ) { # assume that it's MySQL 4.x
-      $name = ($dsn->{h} || 'localhost') . ($dsn->{P} || 3306);
+   if ( $EVAL_ERROR ) {
+      # MySQL 4.x or 5.0
+      PTDEBUG && _d($EVAL_ERROR);
+      $sql = q{SELECT @@hostname};
+      PTDEBUG && _d($sql);
+      ($name) = eval { $dbh->selectrow_array($sql) };
+      if ( $EVAL_ERROR ) {
+         # MySQL 4.x
+         PTDEBUG && _d($EVAL_ERROR);
+         $name = ($dsn->{h} || 'localhost') . ($dsn->{P} || 3306);
+      }
+      else {
+         # MySQL 5.0
+         $sql = q{SHOW VARIABLES LIKE 'port'};
+         PTDEBUG && _d($sql);
+         my (undef, $port) = eval { $dbh->selectrow_array($sql) };
+         PTDEBUG && _d('port:', $port);
+         $name .= $port || '';
+      }
    }
    my $id = md5_hex($name);
 
diff --git a/t/lib/Pingback.t b/t/lib/Pingback.t
index d5058774..87dde73f 100644
--- a/t/lib/Pingback.t
+++ b/t/lib/Pingback.t
@@ -35,11 +35,10 @@ if ( $master_dbh ) {
    (undef, $mysql_distro)
       = $master_dbh->selectrow_array("SHOW VARIABLES LIKE 'version_comment'");
 
-   my $sql    = q{SELECT CONCAT(@@hostname, @@port)};
-   my ($name) = $master_dbh->selectrow_array($sql);
-   $master_id = md5_hex($name);
-
-   (undef, $slave1_id) = Pingback::_generate_identifier( { dbh => $slave1_dbh } );
+   (undef, $master_id) = Pingback::_generate_identifier(
+      { dbh => $master_dbh, dsn => { h => '127.1', P => 12345 }});
+   (undef, $slave1_id) = Pingback::_generate_identifier(
+      { dbh => $slave1_dbh, dsn => { h => '127.1', P => 12346 }});
 
    $master_inst = {
       id   => $master_id,
@@ -283,12 +282,28 @@ is(
 
 SKIP: {
    skip 'Cannot connect to sandbox master', 2 unless $master_dbh;
-   skip 'Requires MySQL 5.0.38 or newer', unless $sandbox_version ge '5.0.38';
 
+   my $expect_master_id;
+   if ( $sandbox_version ge '5.1' ) {
+      my $sql           = q{SELECT CONCAT(@@hostname, @@port)};
+      my ($name)        = $master_dbh->selectrow_array($sql);
+      $expect_master_id = md5_hex($name);
+   }
+   elsif ( $sandbox_version eq '5.0' ) {
+      my $sql           = q{SELECT @@hostname};
+      my ($hostname)    = $master_dbh->selectrow_array($sql);
+      $sql              = q{SHOW VARIABLES LIKE 'port'};
+      my (undef, $port) = $master_dbh->selectrow_array($sql);
+      $expect_master_id = md5_hex($hostname . $port);
+   }
+   else {
+      $expect_master_id = md5_hex("localhost", 12345);
+   }
+   
    is(
-      Pingback::_generate_identifier( { dbh => $master_dbh, dsn => undef } ),
       $master_id,
-      "_generate_identifier() works with a dbh"
+      $expect_master_id,
+      "_generate_identifier() for MySQL $sandbox_version"
    );
 
    # The time limit file already exists (see previous tests), but this is