diff --git a/lib/CharacterData.php b/lib/CharacterData.php
index 130db49..26dd191 100644
--- a/lib/CharacterData.php
+++ b/lib/CharacterData.php
@@ -27,13 +27,12 @@ abstract class CharacterData extends Node {
 
 
     public function appendData(string $data) {
-        // PHP's DOM does this correctly already.
-        return $this->innerNode->appendData($data);
+        $this->innerNode->data .= $data;
     }
 
     public function deleteData(int $offset, int $count) {
         // PHP's DOM does this correctly already.
-        return $this->innerNode->deleteData($data);
+        return $this->innerNode->deleteData($offset, $count);
     }
 
     public function insertData(int $offset, string $data) {
diff --git a/tests/cases/TestCharacterData.php b/tests/cases/TestCharacterData.php
new file mode 100644
index 0000000..a5ac977
--- /dev/null
+++ b/tests/cases/TestCharacterData.php
@@ -0,0 +1,220 @@
+<?php
+/**
+ * @license MIT
+ * Copyright 2017 Dustin Wilson, J. King, et al.
+ * See LICENSE and AUTHORS files for details
+ */
+
+declare(strict_types=1);
+namespace MensBeam\HTML\DOM\TestCase;
+
+use MensBeam\HTML\DOM\{
+    Document,
+    XMLDocument
+};
+
+
+/** @covers \MensBeam\HTML\DOM\CharacterData */
+class TestCharacterData extends \PHPUnit\Framework\TestCase {
+    /**
+     * @covers \MensBeam\HTML\DOM\CharacterData::appendData
+     *
+     * @covers \MensBeam\HTML\DOM\CharacterData::__get_length
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::createCDATASection
+     * @covers \MensBeam\HTML\DOM\Document::createTextNode
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Text::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testMethod_appendData(): void {
+        $d = new Document();
+        $t = $d->createTextNode('ookeek');
+        $this->assertEquals(6, $t->length);
+        $t->appendData('💩');
+        $this->assertEquals(7, $t->length);
+
+        $d = new XMLDocument();
+        $t = $d->createCDATASection('ookeek');
+        $this->assertEquals(6, $t->length);
+        $t->appendData('💩');
+        $this->assertEquals(7, $t->length);
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\CharacterData::deleteData
+     *
+     * @covers \MensBeam\HTML\DOM\CharacterData::__get_data
+     * @covers \MensBeam\HTML\DOM\CharacterData::__set_data
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::createTextNode
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Text::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testMethod_deleteData(): void {
+        $d = new Document();
+        $t = $d->createTextNode('ook eek');
+        $t->deleteData(3, 1);
+        $this->assertSame('ookeek', $t->data);
+        $t->data = 'ook💩eek';
+        $t->deleteData(3, 1);
+        $this->assertSame('ookeek', $t->data);
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\CharacterData::insertData
+     *
+     * @covers \MensBeam\HTML\DOM\CharacterData::__get_data
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::createTextNode
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Text::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testMethod_insertData(): void {
+        $d = new Document();
+        $t = $d->createTextNode('ookeek');
+        $t->insertData(3, '💩');
+        $this->assertSame('ook💩eek', $t->data);
+        $t->insertData(3, '💩');
+        $this->assertSame('ook💩💩eek', $t->data);
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\CharacterData::replaceData
+     *
+     * @covers \MensBeam\HTML\DOM\CharacterData::__get_data
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::createTextNode
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Text::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testMethod_replaceData(): void {
+        $d = new Document();
+        $t = $d->createTextNode('ook💩💩eek');
+        $t->replaceData(3, 2, ' ');
+        $this->assertSame('ook eek', $t->data);
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\CharacterData::substringData
+     *
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::createTextNode
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Text::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testMethod_substringData(): void {
+        $d = new Document();
+        $t = $d->createTextNode('ook💩💩eek');
+        $this->assertSame('💩💩', $t->substringData(3, 2));
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\CharacterData::__get_data
+     * @covers \MensBeam\HTML\DOM\CharacterData::__set_data
+     *
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::createCDATASection
+     * @covers \MensBeam\HTML\DOM\Document::createTextNode
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Text::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testProperty_data(): void {
+        $d = new Document();
+        $t = $d->createTextNode('ook');
+        // Getting is thoroughly tested, setting isn't.
+        $t->data = 'eek';
+        $this->assertSame('eek', $t->data);
+
+        $d = new XMLDocument();
+        $t = $d->createCDATASection('ook');
+        $t->data = 'eek';
+        $this->assertSame('eek', $t->data);
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\CharacterData::__get_length
+     *
+     * @covers \MensBeam\HTML\DOM\CharacterData::__get_data
+     * @covers \MensBeam\HTML\DOM\CharacterData::__set_data
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::createCDATASection
+     * @covers \MensBeam\HTML\DOM\Document::createTextNode
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Text::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::getWrapperNode
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::get
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::has
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::key
+     * @covers \MensBeam\HTML\DOM\Inner\NodeCache::set
+     * @covers \MensBeam\HTML\DOM\Inner\Reflection::createFromProtectedConstructor
+     */
+    public function testProperty_length(): void {
+        $d = new Document();
+        $t = $d->createTextNode('ookeek');
+        $this->assertEquals(6, $t->length);
+        $t->data .= '💩';
+        $this->assertEquals(7, $t->length);
+
+        $d = new XMLDocument();
+        $t = $d->createCDATASection('ookeek');
+        $this->assertEquals(6, $t->length);
+        $t->data .= '💩';
+        $this->assertEquals(7, $t->length);
+    }
+}
\ No newline at end of file
diff --git a/tests/phpunit.dist.xml b/tests/phpunit.dist.xml
index b25ef5e..7d6d314 100644
--- a/tests/phpunit.dist.xml
+++ b/tests/phpunit.dist.xml
@@ -17,6 +17,7 @@
   <testsuites>
     <testsuite name="DOM">
       <file>cases/TestAttr.php</file>
+      <file>cases/TestCharacterData.php</file>
       <file>cases/TestDocument.php</file>
       <file>cases/TestDocumentOrElement.php</file>
       <file>cases/TestDOMImplementation.php</file>