diff --git a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToHtml5DateTimeLocalTransformer.php b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToHtml5LocalDateTimeTransformer.php
similarity index 83%
rename from src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToHtml5DateTimeLocalTransformer.php
rename to src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToHtml5LocalDateTimeTransformer.php
index 041e516483..ed90331266 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToHtml5DateTimeLocalTransformer.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToHtml5LocalDateTimeTransformer.php
@@ -16,17 +16,18 @@ use Symfony\Component\Form\Exception\TransformationFailedException;
 /**
  * @author Franz Wilding <franz.wilding@me.com>
  * @author Bernhard Schussek <bschussek@gmail.com>
+ * @author Fred Cox <mcfedr@gmail.com>
  */
-class DateTimeToHtml5DateTimeLocalTransformer extends BaseDateTimeTransformer
+class DateTimeToHtml5LocalDateTimeTransformer extends BaseDateTimeTransformer
 {
     const HTML5_FORMAT = 'Y-m-d\\TH:i:s';
 
     /**
-     * Transforms a normalized date into a localized date without trailing timezone.
+     * Transforms a \DateTime into a local date and time string.
      *
      * According to the HTML standard, the input string of a datetime-local
      * input is a RFC3339 date followed by 'T', followed by a RFC3339 time.
-     * http://w3c.github.io/html-reference/datatypes.html#form.data.datetime-local
+     * https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#valid-local-date-and-time-string
      *
      * @param \DateTime|\DateTimeInterface $dateTime A DateTime object
      *
@@ -57,7 +58,11 @@ class DateTimeToHtml5DateTimeLocalTransformer extends BaseDateTimeTransformer
     }
 
     /**
-     * Transforms a formatted datetime-local string into a normalized date.
+     * Transforms a local date and time string into a \DateTime.
+     *
+     * When transforming back to DateTime the regex is slightly laxer, taking into
+     * account rules for parsing a local date and time string
+     * https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#parse-a-local-date-and-time-string
      *
      * @param string $dateTimeLocal Formatted string
      *
diff --git a/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php b/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
index 28df7eb7ed..4913957117 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
@@ -15,7 +15,7 @@ use Symfony\Component\Form\AbstractType;
 use Symfony\Component\Form\Extension\Core\DataTransformer\ArrayToPartsTransformer;
 use Symfony\Component\Form\Extension\Core\DataTransformer\DataTransformerChain;
 use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToArrayTransformer;
-use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToHtml5DateTimeLocalTransformer;
+use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToHtml5LocalDateTimeTransformer;
 use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToLocalizedStringTransformer;
 use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToStringTransformer;
 use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToTimestampTransformer;
@@ -75,7 +75,7 @@ class DateTimeType extends AbstractType
 
         if ('single_text' === $options['widget']) {
             if (self::HTML5_FORMAT === $pattern) {
-                $builder->addViewTransformer(new DateTimeToHtml5DateTimeLocalTransformer(
+                $builder->addViewTransformer(new DateTimeToHtml5LocalDateTimeTransformer(
                     $options['model_timezone'],
                     $options['view_timezone']
                 ));
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToHtml5DateTimeLocaleTransformerTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToHtml5LocalDateTimeTransformerTest.php
similarity index 88%
rename from src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToHtml5DateTimeLocaleTransformerTest.php
rename to src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToHtml5LocalDateTimeTransformerTest.php
index f2645ac0c5..5dac998ad1 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToHtml5DateTimeLocaleTransformerTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToHtml5LocalDateTimeTransformerTest.php
@@ -12,9 +12,9 @@
 namespace Symfony\Component\Form\Tests\Extension\Core\DataTransformer;
 
 use PHPUnit\Framework\TestCase;
-use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToHtml5DateTimeLocalTransformer;
+use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToHtml5LocalDateTimeTransformer;
 
-class DateTimeToHtml5DateTimeLocaleTransformerTest extends TestCase
+class DateTimeToHtml5LocalDateTimeTransformerTest extends TestCase
 {
     public static function assertEquals($expected, $actual, $message = '', $delta = 0, $maxDepth = 10, $canonicalize = false, $ignoreCase = false)
     {
@@ -59,7 +59,7 @@ class DateTimeToHtml5DateTimeLocaleTransformerTest extends TestCase
      */
     public function testTransform($fromTz, $toTz, $from, $to)
     {
-        $transformer = new DateTimeToHtml5DateTimeLocalTransformer($fromTz, $toTz);
+        $transformer = new DateTimeToHtml5LocalDateTimeTransformer($fromTz, $toTz);
 
         $this->assertSame($to, $transformer->transform(null !== $from ? new \DateTime($from) : null));
     }
@@ -70,7 +70,7 @@ class DateTimeToHtml5DateTimeLocaleTransformerTest extends TestCase
      */
     public function testTransformDateTimeImmutable($fromTz, $toTz, $from, $to)
     {
-        $transformer = new DateTimeToHtml5DateTimeLocalTransformer($fromTz, $toTz);
+        $transformer = new DateTimeToHtml5LocalDateTimeTransformer($fromTz, $toTz);
 
         $this->assertSame($to, $transformer->transform(null !== $from ? new \DateTimeImmutable($from) : null));
     }
@@ -80,7 +80,7 @@ class DateTimeToHtml5DateTimeLocaleTransformerTest extends TestCase
      */
     public function testTransformRequiresValidDateTime()
     {
-        $transformer = new DateTimeToHtml5DateTimeLocalTransformer();
+        $transformer = new DateTimeToHtml5LocalDateTimeTransformer();
         $transformer->transform('2010-01-01');
     }
 
@@ -89,7 +89,7 @@ class DateTimeToHtml5DateTimeLocaleTransformerTest extends TestCase
      */
     public function testReverseTransform($toTz, $fromTz, $to, $from)
     {
-        $transformer = new DateTimeToHtml5DateTimeLocalTransformer($toTz, $fromTz);
+        $transformer = new DateTimeToHtml5LocalDateTimeTransformer($toTz, $fromTz);
 
         if (null !== $to) {
             $this->assertEquals(new \DateTime($to), $transformer->reverseTransform($from));
@@ -103,7 +103,7 @@ class DateTimeToHtml5DateTimeLocaleTransformerTest extends TestCase
      */
     public function testReverseTransformRequiresString()
     {
-        $transformer = new DateTimeToHtml5DateTimeLocalTransformer();
+        $transformer = new DateTimeToHtml5LocalDateTimeTransformer();
         $transformer->reverseTransform(12345);
     }
 
@@ -112,7 +112,7 @@ class DateTimeToHtml5DateTimeLocaleTransformerTest extends TestCase
      */
     public function testReverseTransformWithNonExistingDate()
     {
-        $transformer = new DateTimeToHtml5DateTimeLocalTransformer('UTC', 'UTC');
+        $transformer = new DateTimeToHtml5LocalDateTimeTransformer('UTC', 'UTC');
 
         $transformer->reverseTransform('2010-04-31T04:05');
     }
@@ -122,7 +122,7 @@ class DateTimeToHtml5DateTimeLocaleTransformerTest extends TestCase
      */
     public function testReverseTransformExpectsValidDateString()
     {
-        $transformer = new DateTimeToHtml5DateTimeLocalTransformer('UTC', 'UTC');
+        $transformer = new DateTimeToHtml5LocalDateTimeTransformer('UTC', 'UTC');
 
         $transformer->reverseTransform('2010-2010-2010');
     }