diff --git a/sql/000_base_structure.sql b/sql/000_base_structure.sql
index d0a3fd48..5f7a3343 100644
--- a/sql/000_base_structure.sql
+++ b/sql/000_base_structure.sql
@@ -182,10 +182,10 @@ CREATE TABLE IF NOT EXISTS `statistics_shares` (
   `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
   `account_id` int(10) unsigned NOT NULL,
   `block_id` int(10) unsigned NOT NULL,
-  `valid` float NOT NULL DEFAULT '0',
-  `invalid` float NOT NULL DEFAULT '0',
-  `pplns_valid` float NOT NULL DEFAULT '0',
-  `pplns_invalid` float NOT NULL DEFAULT '0',
+  `valid` float unsigned NOT NULL DEFAULT '0',
+  `invalid` float unsigned NOT NULL DEFAULT '0',
+  `pplns_valid` float unsigned NOT NULL DEFAULT '0',
+  `pplns_invalid` float unsigned NOT NULL DEFAULT '0',
   PRIMARY KEY (`id`),
   KEY `account_id` (`account_id`),
   KEY `block_id` (`block_id`)
diff --git a/upgrade/definitions/1.0.2_to_1.0.3.inc.php b/upgrade/definitions/1.0.2_to_1.0.3.inc.php
index 4c4a84c1..28f2578d 100644
--- a/upgrade/definitions/1.0.2_to_1.0.3.inc.php
+++ b/upgrade/definitions/1.0.2_to_1.0.3.inc.php
@@ -12,7 +12,7 @@ function run_103() {
   $aSql[] = "ALTER TABLE `blocks` CHANGE `shares` `shares` DOUBLE UNSIGNED DEFAULT NULL;";
   $aSql[] = "UPDATE `statistics_shares` SET `valid` = '0' WHERE `valid` IS NULL;";
   $aSql[] = "UPDATE `statistics_shares` SET `pplns_valid` = '0' WHERE `pplns_valid` IS NULL;";
-  $aSql[] = "ALTER TABLE `statistics_shares` CHANGE `valid` `valid` FLOAT NOT NULL DEFAULT '0', CHANGE `invalid` `invalid` FLOAT NOT NULL DEFAULT '0', CHANGE `pplns_valid` `pplns_valid` FLOAT NOT NULL DEFAULT '0', CHANGE `pplns_invalid` `pplns_invalid` FLOAT NOT NULL DEFAULT '0';";
+  $aSql[] = "ALTER TABLE `statistics_shares` CHANGE `valid` `valid` FLOAT UNSIGNED NOT NULL DEFAULT '0', CHANGE `invalid` `invalid` FLOAT UNSIGNED NOT NULL DEFAULT '0', CHANGE `pplns_valid` `pplns_valid` FLOAT UNSIGNED NOT NULL DEFAULT '0', CHANGE `pplns_invalid` `pplns_invalid` FLOAT UNSIGNED NOT NULL DEFAULT '0';";
   $aSql[] = "UPDATE " . $setting->getTableName() . " SET value = '" . $db_version_new . "' WHERE name = 'DB_VERSION';";
 
   if ($db_version_now == $db_version_old && version_compare($db_version_now, DB_VERSION, '<')) {