diff --git a/phpBB/install/database_update.php b/phpBB/install/database_update.php
index fa0fba9dc7..9d550cf938 100644
--- a/phpBB/install/database_update.php
+++ b/phpBB/install/database_update.php
@@ -1090,6 +1090,9 @@ function database_update_info()
 				GROUPS_TABLE		=> array(
 					'group_legend'		=> array('UINT', 0),
 				),
+				USERS_TABLE			=> array(
+					'user_timezone'		=> array('VCHAR:100', ''),
+				),
 			),
 			'drop_columns'      => array(
 			    STYLES_TABLE		    => array(
@@ -2352,6 +2355,25 @@ function change_database_data(&$no_updates, $version)
 				set_config('teampage_memberships', '1');
 			}
 
+			// Update timezones
+			// user_dst is 0 if not in dst and 1 if in dst;
+			// this happens to be exactly the correction that should be added to the timezone offset
+			// to obtain dst offset.
+			// Parenthesize here because we operate on this value later.
+			$active_offset = '(user_timezone + user_dst)';
+			// Now we have a tricky problem of forcing the plus sign into the expression.
+			// Build it via a conditional since there cannot be a portable printf equivalent in databases.
+			// Note that active offset is not an absolute value here - it is an expression that will
+			// be evaluated by the database during query execution.
+			// We don't print - here because it will come from active offset.
+			$sign = $db->conditional_sql("$active_offset < 0", '', '+');
+			// Use database-specific escaping because strings are quoted differently by different databases.
+			$new_value = $db->concatenate_sql($db->sql_escape('GMT'), $sign, $active_offset);
+			$sql = 'UPDATE ' . USERS_TABLE . '
+				SET user_timezone = ' . $new_value;
+			_sql($sql, $errored, $error_ary);
+			// After we have calculated the timezones we can delete user_dst column from user table.
+
 			$no_updates = false;
 		break;
 	}