diff --git a/src/lib/utils/url-link-converter.js b/src/lib/utils/url-link-converter.js
index cff1cc1..8de7459 100644
--- a/src/lib/utils/url-link-converter.js
+++ b/src/lib/utils/url-link-converter.js
@@ -42,9 +42,12 @@ export function convertUrlsToLinks(text) {
 
 	// Extract code blocks and replace with placeholders
 	while ((codeMatch = codeBlockRegex.exec(text)) !== null) {
-		const placeholder = `__CODE_BLOCK_${codeIndex}__`;
+		const placeholder = createCodeBlockPlaceholder(text, codeIndex);
 		const codeContent = codeMatch[1];
-		codeBlocks.push(`<pre><code>${escapeHtml(codeContent)}</code></pre>`);
+		codeBlocks.push({
+			placeholder,
+			html: `<pre><code>${escapeHtml(codeContent)}</code></pre>`
+		});
 		textWithPlaceholders = textWithPlaceholders.replace(codeMatch[0], placeholder);
 		codeIndex++;
 	}
@@ -86,10 +89,19 @@ export function convertUrlsToLinks(text) {
 	});
 
 	// Restore code blocks from placeholders
-	codeBlocks.forEach((codeBlock, index) => {
-		const placeholder = `__CODE_BLOCK_${index}__`;
-		result = result.replace(placeholder, codeBlock);
+	codeBlocks.forEach((codeBlock) => {
+		result = result.replace(codeBlock.placeholder, codeBlock.html);
 	});
 
 	return result;
 }
+
+function createCodeBlockPlaceholder(text, index) {
+	let suffix = 0;
+	let placeholder;
+	do {
+		placeholder = `\u0000QRYPTCHAT_CODE_BLOCK_${index}_${suffix}\u0000`;
+		suffix++;
+	} while (text.includes(placeholder));
+	return placeholder;
+}
diff --git a/tests/url-link-converter-placeholder.test.js b/tests/url-link-converter-placeholder.test.js
new file mode 100644
index 0000000..ec38899
--- /dev/null
+++ b/tests/url-link-converter-placeholder.test.js
@@ -0,0 +1,14 @@
+import assert from 'node:assert/strict';
+import { describe, it } from 'node:test';
+
+import { convertUrlsToLinks } from '../src/lib/utils/url-link-converter.js';
+
+describe('convertUrlsToLinks code block placeholders', () => {
+	it('does not replace user-authored placeholder-like text with code block HTML', () => {
+		const html = convertUrlsToLinks('literal __CODE_BLOCK_0__ here\n```js\nconsole.log(1)\n```');
+
+		assert.match(html, /literal __CODE_BLOCK_0__ here/);
+		assert.match(html, /<pre><code>js\nconsole\.log\(1\)\n<\/code><\/pre>/);
+		assert.doesNotMatch(html, /<br>__CODE_BLOCK_0__$/);
+	});
+});