diff --git a/src/cheerio.spec.ts b/src/cheerio.spec.ts
index 89d6e0b2ca..ef4f19b83d 100644
--- a/src/cheerio.spec.ts
+++ b/src/cheerio.spec.ts
@@ -443,6 +443,8 @@ describe('cheerio', () => {
       expect(utils.isHtml('<p>fox<p>cat')).toBe(true);
       expect(utils.isHtml('\n<p>fox<p>cat\n')).toBe(true);
       expect(utils.isHtml('#<p>fox<p>cat#')).toBe(true);
+      expect(utils.isHtml('<!-- comment -->')).toBe(true);
+      expect(utils.isHtml('<!doctype html>')).toBe(true);
       expect(utils.isHtml('<123>')).toBe(false);
     });
   });
diff --git a/src/utils.ts b/src/utils.ts
index c343927bdd..88f65930ee 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -113,7 +113,8 @@ export function isHtml(str: string): boolean {
 
   return (
     ((tagChar >= 'a' && tagChar <= 'z') ||
-      (tagChar >= 'A' && tagChar <= 'Z')) &&
+      (tagChar >= 'A' && tagChar <= 'Z') ||
+      tagChar === '!') &&
     str.includes('>', tagStart + 2)
   );
 }
