diff --git a/bin/pt-table-checksum b/bin/pt-table-checksum
index 28ab96ce..6e811f71 100755
--- a/bin/pt-table-checksum
+++ b/bin/pt-table-checksum
@@ -5735,8 +5735,8 @@ sub make_row_checksum {
       $query = join(', ',
                   map { 
                      my $col = $_;
-                     if ( $col =~ m/\+ 0/ ) {
-                        my ($real_col) = /^(\S+)/;
+                     if ( $col =~ m/UNIX_TIMESTAMP/ ) {
+                        my ($real_col) = /^UNIX_TIMESTAMP\((.+?)\)/;
                         $col .= " AS $real_col";
                      }
                      elsif ( $col =~ m/TRIM/ ) {
@@ -5836,7 +5836,7 @@ sub get_checksum_columns {
          my $type   = $tbl_struct->{type_for}->{$_};
          my $result = $q->quote($_);
          if ( $type eq 'timestamp' ) {
-            $result .= ' + 0';
+            $result = "UNIX_TIMESTAMP($result)";
          }
          elsif ( $float_precision && $type =~ m/float|double/ ) {
             $result = "ROUND($result, $float_precision)";
diff --git a/lib/RowChecksum.pm b/lib/RowChecksum.pm
index a8e584dc..3d6e814a 100644
--- a/lib/RowChecksum.pm
+++ b/lib/RowChecksum.pm
@@ -82,10 +82,10 @@ sub make_row_checksum {
       $query = join(', ',
                   map { 
                      my $col = $_;
-                     if ( $col =~ m/\+ 0/ ) {
+                     if ( $col =~ m/UNIX_TIMESTAMP/ ) {
                         # Alias col name back to itself else its name becomes
                         # "col + 0" instead of just "col".
-                        my ($real_col) = /^(\S+)/;
+                        my ($real_col) = /^UNIX_TIMESTAMP\((.+?)\)/;
                         $col .= " AS $real_col";
                      }
                      elsif ( $col =~ m/TRIM/ ) {
@@ -216,7 +216,7 @@ sub get_checksum_columns {
          my $type   = $tbl_struct->{type_for}->{$_};
          my $result = $q->quote($_);
          if ( $type eq 'timestamp' ) {
-            $result .= ' + 0';
+            $result = "UNIX_TIMESTAMP($result)";
          }
          elsif ( $float_precision && $type =~ m/float|double/ ) {
             $result = "ROUND($result, $float_precision)";
diff --git a/t/lib/RowChecksum.t b/t/lib/RowChecksum.t
index 3ef193ea..88403d33 100644
--- a/t/lib/RowChecksum.t
+++ b/t/lib/RowChecksum.t
@@ -126,11 +126,11 @@ is(
       tbl  => $tbl,
       func => 'SHA1',
    ),
-     q{`film_id`, `title`, `description`, `release_year`, `language_id`, `original_language_id`, `rental_duration`, `rental_rate`, `length`, `replacement_cost`, `rating`, `special_features`, `last_update` + 0 AS `last_update`, }
+     q{`film_id`, `title`, `description`, `release_year`, `language_id`, `original_language_id`, `rental_duration`, `rental_rate`, `length`, `replacement_cost`, `rating`, `special_features`, UNIX_TIMESTAMP(`last_update`) AS `last_update`, }
    . q{SHA1(CONCAT_WS('#', }
    . q{`film_id`, `title`, `description`, `release_year`, `language_id`, }
    . q{`original_language_id`, `rental_duration`, `rental_rate`, `length`, }
-   . q{`replacement_cost`, `rating`, `special_features`, `last_update` + 0, }
+   . q{`replacement_cost`, `rating`, `special_features`, UNIX_TIMESTAMP(`last_update`), }
    . q{CONCAT(ISNULL(`description`), ISNULL(`release_year`), }
    . q{ISNULL(`original_language_id`), ISNULL(`length`), }
    . q{ISNULL(`rating`), ISNULL(`special_features`))))},
@@ -142,11 +142,11 @@ is(
       tbl  => $tbl,
       func => 'FNV_64',
    ),
-     q{`film_id`, `title`, `description`, `release_year`, `language_id`, `original_language_id`, `rental_duration`, `rental_rate`, `length`, `replacement_cost`, `rating`, `special_features`, `last_update` + 0 AS `last_update`, }
+     q{`film_id`, `title`, `description`, `release_year`, `language_id`, `original_language_id`, `rental_duration`, `rental_rate`, `length`, `replacement_cost`, `rating`, `special_features`, UNIX_TIMESTAMP(`last_update`) AS `last_update`, }
    . q{FNV_64(}
    . q{`film_id`, `title`, `description`, `release_year`, `language_id`, }
    . q{`original_language_id`, `rental_duration`, `rental_rate`, `length`, }
-   . q{`replacement_cost`, `rating`, `special_features`, `last_update` + 0)},
+   . q{`replacement_cost`, `rating`, `special_features`, UNIX_TIMESTAMP(`last_update`))},
    'FNV_64 query for sakila.film',
 );
 
diff --git a/t/pt-table-checksum/bugs.t b/t/pt-table-checksum/bugs.t
index cf67a889..2d9fb00d 100644
--- a/t/pt-table-checksum/bugs.t
+++ b/t/pt-table-checksum/bugs.t
@@ -294,6 +294,31 @@ like(
    "Bug 1210537: tool ran"
 );
 
+# #############################################################################
+# pt-table-checksum has errors when slaves have different system_time_zone 
+# https://bugs.launchpad.net/percona-toolkit/+bug/1388870 
+# #############################################################################
+
+# make slave set diferent system_time_zone by changing env var TZ. 
+diag(`/tmp/12346/stop >/dev/null`); 
+diag(`export TZ='HST';/tmp/12346/start >/dev/null`); 
+
+$output = output(
+   sub { pt_table_checksum::main(@args, qw(-t sakila.payment)) },
+);
+
+
+is(
+   PerconaTest::count_checksum_results($output, 'diffs'),
+   0,
+   "Bug 1388870 - No false positive reported when system_tz differ on slave"
+);
+
+# restore slave to original system_tz 
+diag(`/tmp/12346/stop >/dev/null`); 
+diag(`/tmp/12346/start >/dev/null`); 
+
+
 # #############################################################################
 # Done.
 # #############################################################################
diff --git a/t/pt-table-checksum/samples/chunkidx004.txt b/t/pt-table-checksum/samples/chunkidx004.txt
index b3ceb684..31b89632 100644
--- a/t/pt-table-checksum/samples/chunkidx004.txt
+++ b/t/pt-table-checksum/samples/chunkidx004.txt
@@ -2,7 +2,7 @@
 -- sakila.city
 --
 
-REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*) AS cnt, COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(CONCAT_WS('#', `city_id`, `city`, `country_id`, `last_update` + 0)) AS UNSIGNED)), 10, 16)), 0) AS crc FROM `sakila`.`city` FORCE INDEX(`idx_fk_country_id`) WHERE ((`country_id` >= ?)) AND ((`country_id` <= ?)) AND (country_id > 100) /*checksum chunk*/
+REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*) AS cnt, COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(CONCAT_WS('#', `city_id`, `city`, `country_id`, UNIX_TIMESTAMP(`last_update`))) AS UNSIGNED)), 10, 16)), 0) AS crc FROM `sakila`.`city` FORCE INDEX(`idx_fk_country_id`) WHERE ((`country_id` >= ?)) AND ((`country_id` <= ?)) AND (country_id > 100) /*checksum chunk*/
 
 REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*), '0' FROM `sakila`.`city` FORCE INDEX(`idx_fk_country_id`) WHERE ((`country_id` < ?)) AND (country_id > 100) ORDER BY `country_id` /*past lower chunk*/
 
diff --git a/t/pt-table-checksum/samples/chunkidx005.txt b/t/pt-table-checksum/samples/chunkidx005.txt
index ae55d193..a6177f19 100644
--- a/t/pt-table-checksum/samples/chunkidx005.txt
+++ b/t/pt-table-checksum/samples/chunkidx005.txt
@@ -2,7 +2,7 @@
 -- sakila.city
 --
 
-REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*) AS cnt, COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(CONCAT_WS('#', `city_id`, `city`, `country_id`, `last_update` + 0)) AS UNSIGNED)), 10, 16)), 0) AS crc FROM `sakila`.`city` FORCE INDEX(`PRIMARY`) WHERE ((`city_id` >= ?)) AND ((`city_id` <= ?)) AND (country_id > 100) /*checksum chunk*/
+REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*) AS cnt, COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(CONCAT_WS('#', `city_id`, `city`, `country_id`, UNIX_TIMESTAMP(`last_update`))) AS UNSIGNED)), 10, 16)), 0) AS crc FROM `sakila`.`city` FORCE INDEX(`PRIMARY`) WHERE ((`city_id` >= ?)) AND ((`city_id` <= ?)) AND (country_id > 100) /*checksum chunk*/
 
 REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*), '0' FROM `sakila`.`city` FORCE INDEX(`PRIMARY`) WHERE ((`city_id` < ?)) AND (country_id > 100) ORDER BY `city_id` /*past lower chunk*/
 
diff --git a/t/pt-table-checksum/samples/n-chunk-index-cols.txt b/t/pt-table-checksum/samples/n-chunk-index-cols.txt
index f08f80ea..b8d9e17e 100644
--- a/t/pt-table-checksum/samples/n-chunk-index-cols.txt
+++ b/t/pt-table-checksum/samples/n-chunk-index-cols.txt
@@ -2,7 +2,7 @@
 -- sakila.rental
 --
 
-REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*) AS cnt, COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(CONCAT_WS('#', `rental_id`, `rental_date`, `inventory_id`, `customer_id`, `return_date`, `staff_id`, `last_update` + 0, CONCAT(ISNULL(`return_date`)))) AS UNSIGNED)), 10, 16)), 0) AS crc FROM `sakila`.`rental` FORCE INDEX(`rental_date`) WHERE ((`rental_date` > ?) OR (`rental_date` = ? AND `inventory_id` >= ?)) AND ((`rental_date` < ?) OR (`rental_date` = ? AND `inventory_id` <= ?)) /*checksum chunk*/
+REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*) AS cnt, COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(CONCAT_WS('#', `rental_id`, `rental_date`, `inventory_id`, `customer_id`, `return_date`, `staff_id`, UNIX_TIMESTAMP(`last_update`), CONCAT(ISNULL(`return_date`)))) AS UNSIGNED)), 10, 16)), 0) AS crc FROM `sakila`.`rental` FORCE INDEX(`rental_date`) WHERE ((`rental_date` > ?) OR (`rental_date` = ? AND `inventory_id` >= ?)) AND ((`rental_date` < ?) OR (`rental_date` = ? AND `inventory_id` <= ?)) /*checksum chunk*/
 
 REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*), '0' FROM `sakila`.`rental` FORCE INDEX(`rental_date`) WHERE ((`rental_date` < ?) OR (`rental_date` = ? AND `inventory_id` < ?)) ORDER BY `rental_date`, `inventory_id`, `customer_id` /*past lower chunk*/