diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9a7cf08..79fdcbf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,12 +10,25 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Added
 
+* Add `ValidatorInterface::getPattern()` to return the regular expression
+  pattern used by the validator.
+* Add `v6()` helper function for version 6 UUIDs.
+
 ### Changed
 
+* Set the pattern constants on validators as `private`. Use the `getPattern()`
+  method instead.
+* Change the `$node` parameter for `UuidFactoryInterface::uuid6()` to accept
+  `null` or `Type\Hexadecimal`.
+
 ### Deprecated
 
 ### Removed
 
+* Remove `currentTime()` method from `Provider\Time\FixedTimeProvider` and
+  `Provider\Time\SystemTimeProvider`; it had previously been removed from
+  `Provider\TimeProviderInterface`.
+
 ### Fixed
 
 ### Security
diff --git a/src/Uuid.php b/src/Uuid.php
index 99cb9a1..a0d1dd1 100644
--- a/src/Uuid.php
+++ b/src/Uuid.php
@@ -545,8 +545,8 @@ class Uuid implements UuidInterface
      * Returns a version 6 (ordered-time) UUID from a host ID, sequence number,
      * and the current time
      *
-     * @param int|string $node A 48-bit number representing the hardware address;
-     *     this number may be represented as an integer or a hexadecimal string
+     * @param Hexadecimal|null $node A 48-bit number representing the hardware
+     *     address
      * @param int $clockSeq A 14-bit number used to help avoid duplicates that
      *     could arise when the clock is set backwards in time or if the node ID
      *     changes
@@ -554,8 +554,10 @@ class Uuid implements UuidInterface
      * @return UuidInterface A UuidInterface instance that represents a
      *     version 6 UUID
      */
-    public static function uuid6($node = null, ?int $clockSeq = null): UuidInterface
-    {
+    public static function uuid6(
+        ?Hexadecimal $node = null,
+        ?int $clockSeq = null
+    ): UuidInterface {
         return self::getFactory()->uuid6($node, $clockSeq);
     }
 }
diff --git a/src/UuidFactory.php b/src/UuidFactory.php
index acb52f9..afa17d4 100644
--- a/src/UuidFactory.php
+++ b/src/UuidFactory.php
@@ -353,12 +353,10 @@ class UuidFactory implements UuidFactoryInterface
         return $this->uuidFromNsAndName($ns, $name, 5, 'sha1');
     }
 
-    /**
-     * @inheritDoc
-     */
-    public function uuid6($node = null, ?int $clockSeq = null): UuidInterface
+    public function uuid6(?Hexadecimal $node = null, ?int $clockSeq = null): UuidInterface
     {
-        $bytes = $this->timeGenerator->generate($node, $clockSeq);
+        $nodeHex = $node ? $node->toString() : null;
+        $bytes = $this->timeGenerator->generate($nodeHex, $clockSeq);
 
         // Rearrange the bytes, according to the UUID version 6 specification.
         $v6 = $bytes[6] . $bytes[7] . $bytes[4] . $bytes[5]
diff --git a/src/UuidFactoryInterface.php b/src/UuidFactoryInterface.php
index 03505e1..ec2ddb8 100644
--- a/src/UuidFactoryInterface.php
+++ b/src/UuidFactoryInterface.php
@@ -109,8 +109,8 @@ interface UuidFactoryInterface
      * Returns a version 6 (ordered-time) UUID from a host ID, sequence number,
      * and the current time
      *
-     * @param int|string $node A 48-bit number representing the hardware address;
-     *     this number may be represented as an integer or a hexadecimal string
+     * @param Hexadecimal|null $node A 48-bit number representing the hardware
+     *     address
      * @param int $clockSeq A 14-bit number used to help avoid duplicates that
      *     could arise when the clock is set backwards in time or if the node ID
      *     changes
@@ -118,7 +118,7 @@ interface UuidFactoryInterface
      * @return UuidInterface A UuidInterface instance that represents a
      *     version 6 UUID
      */
-    public function uuid6($node = null, ?int $clockSeq = null): UuidInterface;
+    public function uuid6(?Hexadecimal $node = null, ?int $clockSeq = null): UuidInterface;
 
     /**
      * Creates a UUID from a byte string
diff --git a/src/functions.php b/src/functions.php
index 2eb8f42..b148447 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -27,6 +27,8 @@ use Ramsey\Uuid\Type\Integer as IntegerObject;
  * @param int $clockSeq A 14-bit number used to help avoid duplicates that
  *     could arise when the clock is set backwards in time or if the node ID
  *     changes
+ *
+ * @return string Version 1 UUID as a string
  */
 function v1($node = null, ?int $clockSeq = null): string
 {
@@ -48,6 +50,8 @@ function v1($node = null, ?int $clockSeq = null): string
  * @param int|null $clockSeq A 14-bit number used to help avoid duplicates
  *     that could arise when the clock is set backwards in time or if the
  *     node ID changes
+ *
+ * @return string Version 2 UUID as a string
  */
 function v2(
     int $localDomain,
@@ -63,6 +67,8 @@ function v2(
  * namespace ID and a name
  *
  * @param string|UuidInterface $ns The namespace (must be a valid UUID)
+ *
+ * @return string Version 3 UUID as a string
  */
 function v3($ns, string $name): string
 {
@@ -71,6 +77,8 @@ function v3($ns, string $name): string
 
 /**
  * Returns a version 4 (random) UUID
+ *
+ * @return string Version 4 UUID as a string
  */
 function v4(): string
 {
@@ -82,8 +90,27 @@ function v4(): string
  * namespace ID and a name
  *
  * @param string|UuidInterface $ns The namespace (must be a valid UUID)
+ *
+ * @return string Version 5 UUID as a string
  */
 function v5($ns, string $name): string
 {
     return Uuid::uuid5($ns, $name)->toString();
 }
+
+/**
+ * Returns a version 6 (ordered-time) UUID from a host ID, sequence number,
+ * and the current time
+ *
+ * @param Hexadecimal|null $node A 48-bit number representing the hardware
+ *     address
+ * @param int $clockSeq A 14-bit number used to help avoid duplicates that
+ *     could arise when the clock is set backwards in time or if the node ID
+ *     changes
+ *
+ * @return string Version 6 UUID as a string
+ */
+function v6(?Hexadecimal $node = null, ?int $clockSeq = null): string
+{
+    return Uuid::uuid6($node, $clockSeq)->toString();
+}
diff --git a/tests/FunctionsTest.php b/tests/FunctionsTest.php
index 26d84c1..399d533 100644
--- a/tests/FunctionsTest.php
+++ b/tests/FunctionsTest.php
@@ -14,6 +14,7 @@ use function Ramsey\Uuid\v2;
 use function Ramsey\Uuid\v3;
 use function Ramsey\Uuid\v4;
 use function Ramsey\Uuid\v5;
+use function Ramsey\Uuid\v6;
 
 class FunctionsTest extends TestCase
 {
@@ -66,4 +67,18 @@ class FunctionsTest extends TestCase
         $this->assertIsString($v5);
         $this->assertSame(Uuid::UUID_TYPE_HASH_SHA1, Uuid::fromString($v5)->getVersion());
     }
+
+    public function testV6ReturnsVersion6UuidString(): void
+    {
+        $v6 = v6(
+            new Hexadecimal('aabbccdd0011'),
+            1234
+        );
+
+        /** @var FieldsInterface $fields */
+        $fields = Uuid::fromString($v6)->getFields();
+
+        $this->assertIsString($v6);
+        $this->assertSame(Uuid::UUID_TYPE_PEABODY, $fields->getVersion());
+    }
 }
diff --git a/tests/UuidTest.php b/tests/UuidTest.php
index 80d3e0c..2a6d3b2 100644
--- a/tests/UuidTest.php
+++ b/tests/UuidTest.php
@@ -553,7 +553,7 @@ class UuidTest extends TestCase
 
     public function testUuid6WithNodeAndClockSequence(): void
     {
-        $uuid = Uuid::uuid6('0800200c9a66', 0x1669);
+        $uuid = Uuid::uuid6(new Hexadecimal('0800200c9a66'), 0x1669);
         $this->assertInstanceOf(UuidV6::class, $uuid);
         $this->assertInstanceOf(DateTimeInterface::class, $uuid->getDateTime());
         $this->assertSame(2, $uuid->getVariant());
@@ -565,7 +565,7 @@ class UuidTest extends TestCase
 
     public function testUuid6WithHexadecimalNode(): void
     {
-        $uuid = Uuid::uuid6('7160355e');
+        $uuid = Uuid::uuid6(new Hexadecimal('7160355e'));
 
         $this->assertInstanceOf(UuidV6::class, $uuid);
         $this->assertInstanceOf(DateTimeInterface::class, $uuid->getDateTime());
@@ -576,7 +576,7 @@ class UuidTest extends TestCase
 
     public function testUuid6WithMixedCaseHexadecimalNode(): void
     {
-        $uuid = Uuid::uuid6('71B0aD5e');
+        $uuid = Uuid::uuid6(new Hexadecimal('71B0aD5e'));
 
         $this->assertInstanceOf(Uuid::class, $uuid);
         $this->assertInstanceOf(DateTimeInterface::class, $uuid->getDateTime());
@@ -590,15 +590,7 @@ class UuidTest extends TestCase
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('Invalid node value');
 
-        Uuid::uuid6('9223372036854775808');
-    }
-
-    public function testUuid6WithNonHexadecimalNode(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        $this->expectExceptionMessage('Invalid node value');
-
-        Uuid::uuid6('db77e160355g');
+        Uuid::uuid6(new Hexadecimal('9223372036854775808'));
     }
 
     public function testUuid6WithNon48bitNumber(): void
@@ -606,7 +598,7 @@ class UuidTest extends TestCase
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('Invalid node value');
 
-        Uuid::uuid6('db77e160355ef');
+        Uuid::uuid6(new Hexadecimal('db77e160355ef'));
     }
 
     public function testUuid6WithRandomNode(): void