diff --git a/src/Html5/InlineTextSemantics/TimeTag.php b/src/Html5/InlineTextSemantics/TimeTag.php
index f64ea29..59d7a0e 100644
--- a/src/Html5/InlineTextSemantics/TimeTag.php
+++ b/src/Html5/InlineTextSemantics/TimeTag.php
@@ -4,9 +4,6 @@ namespace ByJoby\HTML\Html5\InlineTextSemantics;
 
 use ByJoby\HTML\Html5\InlineTextSemantics\TimeTag\DatetimeValue;
 use ByJoby\HTML\Tags\AbstractContainerTag;
-use DateInterval;
-use DateTimeInterface;
-use Stringable;
 
 /**
  * The <time> HTML element represents a specific period in time. It may include
diff --git a/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue.php b/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue.php
index 2761650..cb122e1 100644
--- a/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue.php
+++ b/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue.php
@@ -55,7 +55,7 @@ abstract class DatetimeValue implements StringableValue
      * Matches any integer from 00 to 59, leading zero optional. Optionally
      * followed by a three-digit decimal portion.
      */
-    const REGEX_SECOND = '((?<second>0?[0-9]|[1-5][0-9])(\.(?<microsecond>[0-9]{3}))?)';
+    const REGEX_SECOND = '((?<second>0?[0-9]|[1-5][0-9])(\.(?<millisecond>[0-9]{3}))?)';
 
     /**
      * Tries parsing with all subclasses and returns the first one that
diff --git a/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_datetime_local.php b/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_datetime_local.php
index 16d43ed..64c2f61 100644
--- a/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_datetime_local.php
+++ b/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_datetime_local.php
@@ -14,9 +14,6 @@ use Stringable;
  */
 class DatetimeValue_datetime_local extends DatetimeValue
 {
-    /** @var DateTime */
-    public $datetime;
-
     public static function fromString(string|Stringable|null $string): null|self
     {
         // null string returns null
@@ -38,24 +35,26 @@ class DatetimeValue_datetime_local extends DatetimeValue
             )
         ) {
             return new self(
-                intval($matches['year']),
-                intval($matches['month']),
-                intval($matches['day']),
-                intval($matches['hour']),
-                intval($matches['minute']),
-                intval(@$matches['second']),
-                intval(@$matches['millisecond'])
+                (new DateTime())
+                    ->setDate(
+                        intval($matches['year']),
+                        intval($matches['month']),
+                        intval($matches['day'])
+                    )
+                    ->setTime(
+                        intval($matches['hour']),
+                        intval($matches['minute']),
+                        intval(@$matches['second']),
+                        intval(@$matches['millisecond']) * 1000
+                    )
             );
         }
         // return null if nothing found
         return null;
     }
 
-    public function __construct(int $year, int $month, int $day, int $hour, int $minute, int $second = 0, int $millisecond = 0)
+    public function __construct(public DateTime $datetime)
     {
-        $this->datetime = (new DateTime())
-            ->setDate($year, $month, $day)
-            ->setTime($hour, $minute, $second, $millisecond * 1000);
     }
 
     public function __toString()
diff --git a/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_time.php b/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_time.php
index 39c49b7..bd07816 100644
--- a/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_time.php
+++ b/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_time.php
@@ -37,7 +37,7 @@ class DatetimeValue_time extends DatetimeValue
                 intval($matches['hour']),
                 intval($matches['minute']),
                 intval(@$matches['second']),
-                intval(@$matches['microsecond'])
+                intval(@$matches['millisecond'])
             );
         }
         // return null if nothing found
@@ -47,7 +47,12 @@ class DatetimeValue_time extends DatetimeValue
     public function __construct(int $hour, int $minute, int $second = 0, int $millisecond = 0)
     {
         $this->datetime = (new DateTime())
-            ->setTime($hour, $minute, $second, $millisecond*1000);
+            ->setTime(
+                $hour,
+                $minute,
+                $second,
+                $millisecond * 1000
+            );
     }
 
     public function __toString()
diff --git a/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_week.php b/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_week.php
index 7711a88..24b1924 100644
--- a/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_week.php
+++ b/src/Html5/InlineTextSemantics/TimeTag/DatetimeValue_week.php
@@ -41,7 +41,7 @@ class DatetimeValue_week extends DatetimeValue
     public function __toString()
     {
         return sprintf(
-            '%s%04d-%02d',
+            '%s%04d-W%02d',
             $this->year < 0 ? '-' : '',
             abs($this->year),
             $this->week
diff --git a/tests/Html5/InlineTextSemantics/TimeTag/DatetimeValue_date_week_Test.php b/tests/Html5/InlineTextSemantics/TimeTag/DatetimeValue_date_week_Test.php
index 8ecfddb..d638a5f 100644
--- a/tests/Html5/InlineTextSemantics/TimeTag/DatetimeValue_date_week_Test.php
+++ b/tests/Html5/InlineTextSemantics/TimeTag/DatetimeValue_date_week_Test.php
@@ -26,10 +26,10 @@ class DatetimeValue_week_Test extends TestCase
             DatetimeValue_week::fromString("99999-W53")
                     ?->__toString()
         );
-        // negative year
+        // negative year less than 4 digits
         $this->assertEquals(
-            "-1500-06",
-            DatetimeValue_week::fromString("-1500-06")
+            "-0150-W06",
+            DatetimeValue_week::fromString("-0150-W06")
                     ?->__toString()
         );
     }