diff --git a/CHANGELOG.md b/CHANGELOG.md
index 14c136c..34c7e10 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,11 @@ All notable changes to this add-on will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## Unreleased
+
+### Changed
+- Report index of the forms.
+
 ## 0.0.9 - 2024-11-28
 
 ### Added
diff --git a/source/types/ReportedModel.ts b/source/types/ReportedModel.ts
index e28de8c..3b5baa2 100644
--- a/source/types/ReportedModel.ts
+++ b/source/types/ReportedModel.ts
@@ -113,6 +113,8 @@ class ReportedElement extends ReportedObject {
       // This gets the full URL rather than a relative one
       const a: HTMLAnchorElement = element as HTMLAnchorElement;
       this.href = a.toString();
+    } else if (element.tagName === 'FORM') {
+      this.formId = Array.prototype.slice.call(document.forms).indexOf(element);
     } else if (element.tagName === 'INPUT') {
       // Capture extra useful info for input elements
       const input: HTMLInputElement = element as HTMLInputElement;
diff --git a/test/ContentScript/unitTests.test.ts b/test/ContentScript/unitTests.test.ts
index eae39bd..b784eec 100644
--- a/test/ContentScript/unitTests.test.ts
+++ b/test/ContentScript/unitTests.test.ts
@@ -169,10 +169,10 @@ test('Report page forms', () => {
   // Then
   expect(mockFn.mock.calls.length).toBe(2);
   expect(mockFn.mock.calls[0][0].toNonTimestampString()).toBe(
-    '{"type":"nodeAdded","tagName":"FORM","id":"form1","nodeName":"FORM","url":"http://localhost/","text":"Content1"}'
+    '{"type":"nodeAdded","tagName":"FORM","id":"form1","nodeName":"FORM","url":"http://localhost/","text":"Content1","formId":-1}'
   );
   expect(mockFn.mock.calls[1][0].toNonTimestampString()).toBe(
-    '{"type":"nodeAdded","tagName":"FORM","id":"form2","nodeName":"FORM","url":"http://localhost/","text":"Content2"}'
+    '{"type":"nodeAdded","tagName":"FORM","id":"form2","nodeName":"FORM","url":"http://localhost/","text":"Content2","formId":-1}'
   );
 });
 
@@ -263,7 +263,7 @@ test('Reported page loaded', () => {
     '{"type":"nodeAdded","tagName":"AREA","id":"","nodeName":"AREA","url":"http://localhost/","href":"https://www.example.com/1","text":""}'
   );
   expect(mockFn.mock.calls[2][0].toNonTimestampString()).toBe(
-    '{"type":"nodeAdded","tagName":"FORM","id":"form1","nodeName":"FORM","url":"http://localhost/","text":"FormContent"}'
+    '{"type":"nodeAdded","tagName":"FORM","id":"form1","nodeName":"FORM","url":"http://localhost/","text":"FormContent","formId":-1}'
   );
   expect(mockFn.mock.calls[3][0].toNonTimestampString()).toBe(
     '{"type":"nodeAdded","tagName":"INPUT","id":"input1","nodeName":"INPUT","url":"http://localhost/","text":"default","tagType":"text"}'