diff --git a/client/modules/IDE/hooks/useP5Version.jsx b/client/modules/IDE/hooks/useP5Version.jsx
index a21a7c3b7f..8f52b289bc 100644
--- a/client/modules/IDE/hooks/useP5Version.jsx
+++ b/client/modules/IDE/hooks/useP5Version.jsx
@@ -11,6 +11,7 @@ import {
   p5DataAddonURL,
   p5URLTemplate
 } from '../../../../common/p5URLs';
+import { preserveNoProtect } from '../utils/loopProtection';
 
 export const majorVersion = (version) => version.split('.')[0];
 
@@ -46,7 +47,7 @@ export function P5VersionProvider(props) {
         src = `${doctype}\n${src}`;
       }
 
-      return src;
+      return preserveNoProtect(indexSrc, src);
     };
 
     const usedP5Versions = [...dom.documentElement.querySelectorAll('script')]
diff --git a/client/modules/IDE/hooks/useP5Version.unit.test.jsx b/client/modules/IDE/hooks/useP5Version.unit.test.jsx
new file mode 100644
index 0000000000..2ad73628b5
--- /dev/null
+++ b/client/modules/IDE/hooks/useP5Version.unit.test.jsx
@@ -0,0 +1,87 @@
+import React from 'react';
+import { reduxRender } from '../../../test-utils';
+import { initialState as filesInitialState } from '../reducers/files';
+import { p5PreloadAddonURL } from '../../../../common/p5URLs';
+import { hasNoProtect } from '../utils/loopProtection';
+import { P5VersionProvider, useP5Version } from './useP5Version';
+
+const P5_SCRIPT = 'https://cdn.jsdelivr.net/npm/p5@2.3.2/lib/p5.js';
+
+function indexHtml({ noprotect = false, sound = false } = {}) {
+  const soundTag = sound
+    ? '\n    <script src="https://cdn.jsdelivr.net/npm/p5.sound@0.4.1/dist/p5.sound.min.js"></script>'
+    : '';
+  const html = `<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <script src="${P5_SCRIPT}"></script>${soundTag}
+  </head>
+  <body></body>
+</html>`;
+  return noprotect ? `<!-- noprotect -->\n${html}` : html;
+}
+
+let capturedVersionInfo = null;
+
+function VersionProbe() {
+  const { versionInfo } = useP5Version();
+  capturedVersionInfo = versionInfo;
+  return null;
+}
+
+function renderVersionInfo(indexContent) {
+  capturedVersionInfo = null;
+  reduxRender(
+    <P5VersionProvider>
+      <VersionProbe />
+    </P5VersionProvider>,
+    {
+      initialState: {
+        files: filesInitialState().map((file) => ({
+          ...file,
+          ...(file.fileType === 'file' &&
+            file.name === 'index.html' &&
+            file.filePath === '' && { content: indexContent })
+        }))
+      }
+    }
+  );
+  return capturedVersionInfo;
+}
+
+describe('useP5Version HTML rewrites', () => {
+  afterEach(() => {
+    capturedVersionInfo = null;
+  });
+
+  it('keeps <!-- noprotect --> when replaceVersion rewrites index.html', () => {
+    const versionInfo = renderVersionInfo(indexHtml({ noprotect: true }));
+    const next = versionInfo.replaceVersion('2.3.3');
+
+    expect(hasNoProtect(next)).toBe(true);
+    expect(next).toContain('p5@2.3.3/lib/p5.js');
+    expect(next.match(/<!--\s*noprotect\s*-->/g)).toHaveLength(1);
+  });
+
+  it('does not insert <!-- noprotect --> when the original had none', () => {
+    const versionInfo = renderVersionInfo(indexHtml());
+    const next = versionInfo.replaceVersion('2.3.3');
+
+    expect(hasNoProtect(next)).toBe(false);
+    expect(next).toContain('p5@2.3.3/lib/p5.js');
+  });
+
+  it('keeps <!-- noprotect --> when addon setters rewrite index.html', () => {
+    const versionInfo = renderVersionInfo(
+      indexHtml({ noprotect: true, sound: true })
+    );
+
+    const afterSoundOff = versionInfo.setP5Sound(false);
+    expect(hasNoProtect(afterSoundOff)).toBe(true);
+    expect(afterSoundOff).not.toContain('p5.sound');
+
+    const afterPreload = versionInfo.setP5PreloadAddon(true);
+    expect(hasNoProtect(afterPreload)).toBe(true);
+    expect(afterPreload).toContain(p5PreloadAddonURL);
+  });
+});
diff --git a/client/modules/IDE/utils/loopProtection.js b/client/modules/IDE/utils/loopProtection.js
index 49e591496a..72af02872c 100644
--- a/client/modules/IDE/utils/loopProtection.js
+++ b/client/modules/IDE/utils/loopProtection.js
@@ -16,3 +16,11 @@ export function removeNoProtect(src = '') {
 export function toggleLoopProtection(src = '', enabled) {
   return enabled ? removeNoProtect(src) : addNoProtect(src);
 }
+
+// Version/addon HTML rewrites serialize via documentElement.outerHTML, which
+// drops comments outside <html> — including a leading <!-- noprotect -->.
+export function preserveNoProtect(originalSrc = '', serializedSrc = '') {
+  return hasNoProtect(originalSrc)
+    ? addNoProtect(serializedSrc)
+    : serializedSrc;
+}
diff --git a/client/modules/IDE/utils/loopProtection.unit.test.js b/client/modules/IDE/utils/loopProtection.unit.test.js
new file mode 100644
index 0000000000..d9483a775d
--- /dev/null
+++ b/client/modules/IDE/utils/loopProtection.unit.test.js
@@ -0,0 +1,64 @@
+import {
+  addNoProtect,
+  hasNoProtect,
+  preserveNoProtect,
+  removeNoProtect,
+  toggleLoopProtection
+} from './loopProtection';
+
+describe('loopProtection helpers', () => {
+  const html = `<!DOCTYPE html>
+<html>
+  <head></head>
+  <body></body>
+</html>`;
+  const withNoProtect = `<!-- noprotect -->\n${html}`;
+
+  describe('hasNoProtect', () => {
+    it('is true when a leading noprotect comment exists', () => {
+      expect(hasNoProtect(withNoProtect)).toBe(true);
+    });
+
+    it('is false when the comment is absent', () => {
+      expect(hasNoProtect(html)).toBe(false);
+    });
+  });
+
+  describe('addNoProtect / removeNoProtect', () => {
+    it('prepends the comment once', () => {
+      expect(addNoProtect(html)).toBe(withNoProtect);
+      expect(addNoProtect(withNoProtect)).toBe(withNoProtect);
+    });
+
+    it('strips the comment', () => {
+      expect(removeNoProtect(withNoProtect)).toBe(html);
+      expect(removeNoProtect(html)).toBe(html);
+    });
+  });
+
+  describe('toggleLoopProtection', () => {
+    it('removes noprotect when protection is enabled', () => {
+      expect(toggleLoopProtection(withNoProtect, true)).toBe(html);
+    });
+
+    it('adds noprotect when protection is disabled', () => {
+      expect(toggleLoopProtection(html, false)).toBe(withNoProtect);
+    });
+  });
+
+  describe('preserveNoProtect', () => {
+    it('restores noprotect after a rewrite that dropped it', () => {
+      expect(preserveNoProtect(withNoProtect, html)).toBe(withNoProtect);
+    });
+
+    it('does not insert noprotect when the original had none', () => {
+      expect(preserveNoProtect(html, html)).toBe(html);
+    });
+
+    it('does not duplicate noprotect when the rewrite kept it', () => {
+      expect(preserveNoProtect(withNoProtect, withNoProtect)).toBe(
+        withNoProtect
+      );
+    });
+  });
+});