diff --git a/spec/heading_anchors.spec.php b/spec/heading_anchors.spec.php
new file mode 100644
index 0000000..704b712
--- /dev/null
+++ b/spec/heading_anchors.spec.php
@@ -0,0 +1,30 @@
+<?php
+
+namespace LongReadPlugin;
+
+describe(HeadingAnchors::class, function () {
+    beforeEach(function () {
+        $this->headingAnchors = new HeadingAnchors();
+    });
+
+    it('is registrable', function () {
+        expect($this->headingAnchors)->toBeAnInstanceOf(\Dxw\Iguana\Registerable::class);
+    });
+
+    describe('->register()', function () {
+        it('adds the filter', function () {
+            allow('add_filter')->toBeCalled();
+            expect('add_filter')->toBeCalled()->once();
+            expect('add_filter')->toBeCalled()->with('block_editor_settings_all', [$this->headingAnchors, 'enforceAnchors']);
+            $this->headingAnchors->register();
+        });
+    });
+
+    describe('->enforceAnchors', function () {
+        it('sets __experimentalGenerateAnchors to true', function () {
+            $settings = [];
+            $result = $this->headingAnchors->enforceAnchors($settings);
+            expect($result['__experimentalGenerateAnchors'])->toEqual(true);
+        });
+    });
+});
diff --git a/src/HeadingAnchors.php b/src/HeadingAnchors.php
new file mode 100644
index 0000000..ec2ac69
--- /dev/null
+++ b/src/HeadingAnchors.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace LongReadPlugin;
+
+class HeadingAnchors implements \Dxw\Iguana\Registerable
+{
+    public function register() : void
+    {
+        add_filter('block_editor_settings_all', [$this, 'enforceAnchors']);
+    }
+
+    public function enforceAnchors(array $settings) : array
+    {
+        $settings['__experimentalGenerateAnchors'] = true;
+        return $settings;
+    }
+}