diff --git a/lib/Attr.php b/lib/Attr.php
index 2a14cfe..be3870e 100644
--- a/lib/Attr.php
+++ b/lib/Attr.php
@@ -18,9 +18,10 @@ class Attr extends Node {
     }
 
     protected function __get_name(): string {
-        // PHP's DOM does this correctly already.
+        // PHP's DOM incorrectly returns the local name instead of the qualified name
+        // per the specification.
         // Need to uncoerce string if necessary.
-        $name = $this->innerNode->name;
+        $name = $this->innerNode->nodeName;
         return (!str_contains(needle: 'U', haystack: $name)) ? $name : $this->uncoerceName($name);
     }
 
diff --git a/lib/HTMLCollection.php b/lib/HTMLCollection.php
index 4748363..6ae41f3 100644
--- a/lib/HTMLCollection.php
+++ b/lib/HTMLCollection.php
@@ -45,4 +45,8 @@ class HTMLCollection extends Collection {
     public function offsetGet($offset): ?Element {
         return (is_int($offset)) ? $this->item($offset) : $this->namedItem($offset);
     }
+
+    public function offsetExists($offset): bool {
+        return (((is_int($offset)) ? $this->item($offset) : $this->namedItem($offset)) !== null);
+    }
 }
\ No newline at end of file
diff --git a/lib/NamedNodeMap.php b/lib/NamedNodeMap.php
index c31c635..b1a8a3b 100644
--- a/lib/NamedNodeMap.php
+++ b/lib/NamedNodeMap.php
@@ -7,10 +7,16 @@
 
 declare(strict_types=1);
 namespace MensBeam\HTML\DOM;
-use MensBeam\HTML\DOM\Inner\Document as InnerDocument;
+use MensBeam\HTML\DOM\Inner\{
+    Document as InnerDocument,
+    Reflection
+};
+use MensBeam\HTML\Parser\NameCoercion;
 
 
 class NamedNodeMap extends Collection {
+    use NameCoercion;
+
     # A NamedNodeMap has an associated element (an element).
     protected Element $element;
 
@@ -43,6 +49,53 @@ class NamedNodeMap extends Collection {
         return parent::item($index);
     }
 
+    public function offsetGet($offset): ?Attr {
+        if (is_int($offset)) {
+            return $this->item($offset);
+        }
+
+        # A NamedNodeMap object’s supported property names are the return value of running
+        # these steps:
+        # 1. Let names be the qualified names of the attributes in this NamedNodeMap object’s
+        #    attribute list, with duplicates omitted, in order.
+        // The spec is extremely vague as to what to do here, but it seems to expect
+        // this to be some sort of live private property that the class will poll to
+        // check for valid property names when trying to access them. This is
+        // inefficient. Going to do basically the same thing but not return a list of
+        // every one. It will just search the element's attribute list instead using the
+        // same process.
+
+        # 2. If this NamedNodeMap object’s element is in the HTML namespace and its node
+        #    document is an HTML document, then for each name in names:
+        #    1. Let lowercaseName be name, in ASCII lowercase.
+        #    2. If lowercaseName is not equal to name, remove name from names.
+        # 3. Return names.
+
+        $innerElement = Reflection::getProtectedProperty($this->element, 'innerNode');
+        $innerDocument = $innerElement->ownerDocument;
+        $attributes = $innerElement->attributes;
+        if ($attributes->length > 0) {
+            $coercedOffset = $this->coerceName($offset);
+
+            foreach ($attributes as $attr) {
+                $name = $attr->nodeName;
+                if ($this->element->namespaceURI === Node::HTML_NAMESPACE && $name !== strtolower($name)) {
+                    continue;
+                }
+
+                if ($name === $offset || $name === $coercedOffset) {
+                    return $innerDocument->getWrapperNode($attr);
+                }
+            }
+        }
+
+        return null;
+    }
+
+    public function offsetExists($offset): bool {
+        return (((is_int($offset)) ? $this->item($offset) : $this->getNamedItem($offset)) !== null);
+    }
+
     public function removeNamedItem(string $qualifiedName): ?Attr {
         return $this->removeNamedItemNS(null, $qualifiedName);
     }
diff --git a/tests/cases/TestAttr.php b/tests/cases/TestAttr.php
index 8665faa..8a5bfb7 100644
--- a/tests/cases/TestAttr.php
+++ b/tests/cases/TestAttr.php
@@ -27,7 +27,7 @@ class TestAttr extends \PHPUnit\Framework\TestCase {
         // Coerced name
         $this->assertSame('poop💩', $body->getAttributeNode('poop💩')->name);
         // Foreign attribute name
-        $this->assertSame('xlink', $svg->getAttributeNodeNS(Node::XMLNS_NAMESPACE, 'xlink')->name);
+        $this->assertSame('xmlns:xlink', $svg->getAttributeNodeNS(Node::XMLNS_NAMESPACE, 'xlink')->name);
     }
 
     public function testProperty_prefix(): void {
diff --git a/tests/cases/TestCollection.php b/tests/cases/TestCollection.php
new file mode 100644
index 0000000..8295061
--- /dev/null
+++ b/tests/cases/TestCollection.php
@@ -0,0 +1,94 @@
+<?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\{
+    Attr,
+    Document,
+    HTMLElement
+};
+
+
+/** @covers \MensBeam\HTML\DOM\Collection */
+class TestCollection extends \PHPUnit\Framework\TestCase {
+    /**
+     * @covers \MensBeam\HTML\DOM\Collection::current
+     * @covers \MensBeam\HTML\DOM\Collection::item
+     * @covers \MensBeam\HTML\DOM\Collection::key
+     * @covers \MensBeam\HTML\DOM\Collection::next
+     * @covers \MensBeam\HTML\DOM\Collection::offsetExists
+     * @covers \MensBeam\HTML\DOM\Collection::rewind
+     * @covers \MensBeam\HTML\DOM\Collection::valid
+     *
+     * @covers \MensBeam\HTML\DOM\Collection::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_body
+     * @covers \MensBeam\HTML\DOM\Document::load
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::__get_childNodes
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::hasChildNodes
+     * @covers \MensBeam\HTML\DOM\Node::postParsingTemplatesFix
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__get_xpath
+     * @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 testIteration(): void {
+        $d = new Document('<!DOCTYPE html><html><body><br><br><br><br><br></body></html>');
+        $body = $d->body;
+        $children = $body->childNodes;
+        foreach ($children as $key => $child) {
+            $this->assertTrue($child instanceof HTMLElement);
+        }
+    }
+
+
+    /**
+     * @covers \MensBeam\HTML\DOM\Collection::offsetGet
+     * @covers \MensBeam\HTML\DOM\Collection::offsetUnset
+     *
+     * @covers \MensBeam\HTML\DOM\Attr::__get_value
+     * @covers \MensBeam\HTML\DOM\Collection::item
+     * @covers \MensBeam\HTML\DOM\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Document::__get_body
+     * @covers \MensBeam\HTML\DOM\Document::load
+     * @covers \MensBeam\HTML\DOM\DOMImplementation::__construct
+     * @covers \MensBeam\HTML\DOM\Element::__get_attributes
+     * @covers \MensBeam\HTML\DOM\NamedNodeMap::__construct
+     * @covers \MensBeam\HTML\DOM\NamedNodeMap::item
+     * @covers \MensBeam\HTML\DOM\Node::__construct
+     * @covers \MensBeam\HTML\DOM\Node::getInnerDocument
+     * @covers \MensBeam\HTML\DOM\Node::hasChildNodes
+     * @covers \MensBeam\HTML\DOM\Node::postParsingTemplatesFix
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__construct
+     * @covers \MensBeam\HTML\DOM\Inner\Document::__get_xpath
+     * @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_offsetSet_offsetUnset(): void {
+        $d = new Document('<!DOCTYPE html><html><body a="ook" b="eek" c="ook" d="eek" e="ook"></body></html>');
+        $body = $d->body;
+        $attributes = $body->attributes;
+        $attributes[0] = 'eek';
+        $this->assertSame('ook', $attributes[0]->value);
+        unset($attributes[2]);
+        $this->assertSame('ook', $attributes[2]->value);
+    }
+}
\ No newline at end of file
diff --git a/tests/cases/TestNamedNodeMap.php b/tests/cases/TestNamedNodeMap.php
new file mode 100644
index 0000000..80a33da
--- /dev/null
+++ b/tests/cases/TestNamedNodeMap.php
@@ -0,0 +1,31 @@
+<?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\{
+    Attr,
+    Document,
+    Node
+};
+
+
+/** @covers \MensBeam\HTML\DOM\NamedNodeMap */
+class TestNamedNodeMap extends \PHPUnit\Framework\TestCase {
+    public function testMethod_getOffset(): void {
+        $d = new Document('<!DOCTYPE html><html><body a="ook" b="eek" c="ook" d="eek" e="ook"></body></html>', 'UTF-8');
+        $body = $d->body;
+        $body->setAttributeNS(Node::XMLNS_NAMESPACE, 'xmlns:href', Node::HTML_NAMESPACE);
+        $body->setAttributeNS('https://poop💩.poop', 'poop💩:poop💩', 'poop💩');
+
+        $attributes = $body->attributes;
+        $this->assertSame('ook', $attributes['a']->value);
+        $this->assertSame(Node::HTML_NAMESPACE, $attributes['xmlns:href']->value);
+        $this->assertSame('poop💩', $attributes['poop💩:poop💩']->value);
+    }
+}
\ No newline at end of file
diff --git a/tests/cases/TestNonDocumentTypeChildNode.php b/tests/cases/TestNonDocumentTypeChildNode.php
index 2a74b5e..158b405 100644
--- a/tests/cases/TestNonDocumentTypeChildNode.php
+++ b/tests/cases/TestNonDocumentTypeChildNode.php
@@ -27,6 +27,8 @@ class TestNonDocumentTypeChildNode extends \PHPUnit\Framework\TestCase {
         $br2 = $body->appendChild($d->createElement('br'));
 
         $this->assertSame($br2, $br->nextElementSibling);
+        $this->assertNull($br2->nextElementSibling);
         $this->assertSame($br, $ook->previousElementSibling);
+        $this->assertNull($br->previousElementSibling);
     }
 }
\ No newline at end of file
diff --git a/tests/phpunit.dist.xml b/tests/phpunit.dist.xml
index 5a77177..76b14c8 100644
--- a/tests/phpunit.dist.xml
+++ b/tests/phpunit.dist.xml
@@ -19,12 +19,14 @@
       <file>cases/TestAttr.php</file>
       <file>cases/TestCharacterData.php</file>
       <file>cases/TestChildNode.php</file>
+      <file>cases/TestCollection.php</file>
       <file>cases/TestDocument.php</file>
       <file>cases/TestDocumentOrElement.php</file>
       <file>cases/TestDOMImplementation.php</file>
       <file>cases/TestDOMTokenList.php</file>
       <file>cases/TestElement.php</file>
       <file>cases/TestInnerDocument.php</file>
+      <file>cases/TestNamedNodeMap.php</file>
       <file>cases/TestNode.php</file>
       <file>cases/TestNonDocumentTypeChildNode.php</file>
       <file>cases/TestParentNode.php</file>