diff --git a/UPGRADE.md b/UPGRADE.md
index 33c1452e..4ff4b5ab 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,3 +1,11 @@
+# Upgrade to 0.6
+
+## TitleNode requires an id
+
+The TitleNode constructor is changed to require an ID as 4th argument.
+Similarly, `Doctrine\RST\NodeFactory::createTitleNode()` has been
+updated with an ID as 4th argument.
+
 # Upgrade to 0.5
 
 ## Property visibility changed from protected to private
diff --git a/lib/NodeFactory/DefaultNodeFactory.php b/lib/NodeFactory/DefaultNodeFactory.php
index 4b5fdf2c..d5bdc80a 100644
--- a/lib/NodeFactory/DefaultNodeFactory.php
+++ b/lib/NodeFactory/DefaultNodeFactory.php
@@ -78,9 +78,9 @@ public function createTocNode(Environment $environment, array $files, array $opt
         return $tocNode;
     }
 
-    public function createTitleNode(Node $value, int $level, string $token): TitleNode
+    public function createTitleNode(Node $value, int $level, string $token, string $id): TitleNode
     {
-        $titleNode = $this->create(NodeTypes::TITLE, [$value, $level, $token]);
+        $titleNode = $this->create(NodeTypes::TITLE, [$value, $level, $token, $id]);
         assert($titleNode instanceof TitleNode);
 
         return $titleNode;
diff --git a/lib/NodeFactory/NodeFactory.php b/lib/NodeFactory/NodeFactory.php
index b6ffa40a..85284131 100644
--- a/lib/NodeFactory/NodeFactory.php
+++ b/lib/NodeFactory/NodeFactory.php
@@ -45,7 +45,7 @@ public function createDocumentNode(Environment $environment): DocumentNode;
      */
     public function createTocNode(Environment $environment, array $files, array $options): TocNode;
 
-    public function createTitleNode(Node $value, int $level, string $token): TitleNode;
+    public function createTitleNode(Node $value, int $level, string $token, string $id): TitleNode;
 
     public function createSeparatorNode(int $level): SeparatorNode;
 
diff --git a/lib/Nodes/DocumentNode.php b/lib/Nodes/DocumentNode.php
index e818de5d..b52075bd 100644
--- a/lib/Nodes/DocumentNode.php
+++ b/lib/Nodes/DocumentNode.php
@@ -13,6 +13,7 @@
 use function array_unshift;
 use function assert;
 use function count;
+use function in_array;
 use function is_string;
 use function sprintf;
 
@@ -33,6 +34,9 @@ class DocumentNode extends Node
     /** @var Node[] */
     private $nodes = [];
 
+    /** @var string[] */
+    private $implicitLinkTargets = [];
+
     public function __construct(Environment $environment)
     {
         parent::__construct();
@@ -91,6 +95,24 @@ public function getNodes(?callable $function = null): array
         return $nodes;
     }
 
+    /**
+     * Creates an implicit hyperlink target for this document.
+     *
+     * @param string $preferredId The preferred ID of the hyperlink target, the actual ID is returned by the method (this avoids duplicates)
+     */
+    public function createImplicitLinkTarget(string $preferredId): string
+    {
+        $i        = 1;
+        $actualId = $preferredId;
+        while (in_array($actualId, $this->implicitLinkTargets, true)) {
+            $actualId = $preferredId . '-' . ($i++);
+        }
+
+        $this->implicitLinkTargets[] = $actualId;
+
+        return $actualId;
+    }
+
     public function getTitle(): ?string
     {
         foreach ($this->nodes as $node) {
diff --git a/lib/Nodes/TitleNode.php b/lib/Nodes/TitleNode.php
index a55f3e37..936eabf1 100644
--- a/lib/Nodes/TitleNode.php
+++ b/lib/Nodes/TitleNode.php
@@ -4,8 +4,6 @@
 
 namespace Doctrine\RST\Nodes;
 
-use Doctrine\RST\Environment;
-
 class TitleNode extends Node
 {
     /** @var SpanNode */
@@ -23,13 +21,13 @@ class TitleNode extends Node
     /** @var string */
     private $target = '';
 
-    public function __construct(Node $value, int $level, string $token)
+    public function __construct(Node $value, int $level, string $token, string $id)
     {
         parent::__construct($value);
 
         $this->level = $level;
         $this->token = $token;
-        $this->id    = Environment::slugify($this->value->getText());
+        $this->id    = $id;
     }
 
     public function getValue(): SpanNode
diff --git a/lib/Parser/DocumentParser.php b/lib/Parser/DocumentParser.php
index a6a7b11d..a9ffa4d9 100644
--- a/lib/Parser/DocumentParser.php
+++ b/lib/Parser/DocumentParser.php
@@ -490,11 +490,13 @@ private function flush(): void
                     $level = $this->environment->getConfiguration()->getInitialHeaderLevel() + $level - 1;
 
                     $token = $this->environment->createTitle($level);
+                    $id    = $this->document->createImplicitLinkTarget(Environment::slugify($data));
 
                     $node = $this->nodeFactory->createTitleNode(
                         $this->parser->createSpanNode($data),
                         $level,
-                        $token
+                        $token,
+                        $id
                     );
 
                     if ($this->lastTitleNode !== null) {
diff --git a/tests/DefaultNodeFactoryTest.php b/tests/DefaultNodeFactoryTest.php
index 6954365a..7e80ce49 100644
--- a/tests/DefaultNodeFactoryTest.php
+++ b/tests/DefaultNodeFactoryTest.php
@@ -92,12 +92,12 @@ public function testCreateTitle(): void
 
         $nodeInstantiator->expects(self::once())
             ->method('create')
-            ->with([$node, 1, 'test'])
+            ->with([$node, 1, 'test', 'test'])
             ->willReturn($expectedReturn);
 
         $defaultNodeFactory = $this->createDefaultNodeFactory($nodeInstantiator);
 
-        self::assertSame($expectedReturn, $defaultNodeFactory->createTitleNode($node, 1, 'test'));
+        self::assertSame($expectedReturn, $defaultNodeFactory->createTitleNode($node, 1, 'test', 'test'));
     }
 
     public function testCreateSeparator(): void
diff --git a/tests/Functional/tests/section-nesting/section-nesting.html b/tests/Functional/tests/section-nesting/section-nesting.html
index ce0dcfcc..b25528c9 100644
--- a/tests/Functional/tests/section-nesting/section-nesting.html
+++ b/tests/Functional/tests/section-nesting/section-nesting.html
@@ -37,7 +37,7 @@ <h1>
     <h1>
         Level 1 Test 4
     </h1>
-    <div class="section" id="level-2-test-3">
+    <div class="section" id="level-2-test-3-1">
         <h2>
             Level 2 Test 3
         </h2>
diff --git a/tests/Functional/tests/titles/titles.html b/tests/Functional/tests/titles/titles.html
index 5aba12f8..2805be70 100644
--- a/tests/Functional/tests/titles/titles.html
+++ b/tests/Functional/tests/titles/titles.html
@@ -40,6 +40,11 @@ <h3>
         <h2>
             em
         </h2>
+        <div class="section" id="first-subtitle-1">
+            <h3>
+                First subtitle
+            </h3>
+        </div>
     </div>
 </div>
 <div class="section" id="second-main-title">
diff --git a/tests/Functional/tests/titles/titles.rst b/tests/Functional/tests/titles/titles.rst
index e3021382..39ca8950 100644
--- a/tests/Functional/tests/titles/titles.rst
+++ b/tests/Functional/tests/titles/titles.rst
@@ -30,6 +30,9 @@ Fourth subsubtitle
 em
 --
 
+First subtitle
+~~~~~~~~~~~~~~
+
 Second Main Title
 =================
 
diff --git a/tests/Functional/tests/titles/titles.tex b/tests/Functional/tests/titles/titles.tex
index ec245b9a..8e664515 100644
--- a/tests/Functional/tests/titles/titles.tex
+++ b/tests/Functional/tests/titles/titles.tex
@@ -24,6 +24,9 @@ \subsection{Fourth subsubtitle}
 
 \section{em}
 
+\subsection{First subtitle}
+
+
 
 
 \chapter{Second Main Title}