diff --git a/common/web/types/src/util/util.ts b/common/web/types/src/util/util.ts
index 0d13505cfc..7395c27ba0 100644
--- a/common/web/types/src/util/util.ts
+++ b/common/web/types/src/util/util.ts
@@ -305,6 +305,15 @@ export function isPUA(ch: number) {
     (ch >= Uni_PUA_16_START && ch <= Uni_PUA_16_END));
 }
 
+/** @returns true if s is NEITHER NFC nor NFD */
+export function isDenormalized(s: string) : boolean {
+  if(!s) return false; // empty or null
+  const nfc = s.normalize("NFC");
+  const nfd = s.normalize("NFD");
+  if (s !== nfc && s !== nfd) return true;
+  return false;
+}
+
 class BadStringMap extends Map<BadStringType, Set<number>> {
   public toString() : string {
     if (!this.size) {
diff --git a/common/web/types/test/util/test-unescape.ts b/common/web/types/test/util/test-unescape.ts
index 8c75b49182..853fb6a09b 100644
--- a/common/web/types/test/util/test-unescape.ts
+++ b/common/web/types/test/util/test-unescape.ts
@@ -1,6 +1,6 @@
 import 'mocha';
 import {assert} from 'chai';
-import {unescapeString, UnescapeError, isOneChar, toOneChar, unescapeOneQuadString, BadStringAnalyzer, isValidUnicode, describeCodepoint, isPUA, BadStringType, unescapeStringToRegex, unescapeQuadString, NFDAnalyzer} from '../../src/util/util.js';
+import {unescapeString, UnescapeError, isOneChar, toOneChar, unescapeOneQuadString, BadStringAnalyzer, isValidUnicode, describeCodepoint, isPUA, BadStringType, unescapeStringToRegex, unescapeQuadString, NFDAnalyzer, isDenormalized} from '../../src/util/util.js';
 
 describe('test UTF32 functions()', function() {
   it('should properly categorize strings', () => {
@@ -186,6 +186,24 @@ describe('test bad char functions', () => {
       assert.isTrue(isPUA(ch), describeCodepoint(ch));
     }
   });
+  describe('test isDenormalized()', () => {
+    it('should correctly categorize strings', () => {
+      [
+        undefined,
+        null,
+        '',
+        'ABC',
+        'fa\u1E69cinating', // NFC
+        'fas\u0323\u0307cinating', // NFD
+        'd\u0323\u0307', // NFD
+        '\u1e0d\u0307', // NFC
+      ].map(s => assert.isFalse(isDenormalized(s), `for string ${s}`));
+      [
+        'd\u0307\u0323', // NFD but reversed marks
+        'fas\u0307\u0323cinating', // not-NFD
+      ].map(s => assert.isTrue(isDenormalized(s), `for string ${s}`));
+    });
+  });
 });
 
 describe('test BadStringAnalyzer', () => {