diff --git a/TiaCodegen-ts/package-lock.json b/TiaCodegen-ts/package-lock.json
index 8703977..be4de9c 100644
--- a/TiaCodegen-ts/package-lock.json
+++ b/TiaCodegen-ts/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@node-projects/tia-codegen-ts",
-  "version": "2.0.1",
+  "version": "2.0.2",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@node-projects/tia-codegen-ts",
-      "version": "2.0.1",
+      "version": "2.0.2",
       "devDependencies": {
         "@types/jest": "^29.5.12",
         "@types/node": "^20.12.7",
diff --git a/TiaCodegen-ts/package.json b/TiaCodegen-ts/package.json
index b53e105..b8e6352 100644
--- a/TiaCodegen-ts/package.json
+++ b/TiaCodegen-ts/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@node-projects/tia-codegen-ts",
-  "version": "2.0.1",
+  "version": "2.0.2",
   "description": "TypeScript port of TiaCodeGen C# library",
   "type": "module",
   "main": "dist/index.js",
diff --git a/TiaCodegen-ts/src/Extensions/NaturalComparer.ts b/TiaCodegen-ts/src/Extensions/NaturalComparer.ts
index cf49d0a..b8b51bc 100644
--- a/TiaCodegen-ts/src/Extensions/NaturalComparer.ts
+++ b/TiaCodegen-ts/src/Extensions/NaturalComparer.ts
@@ -22,8 +22,8 @@ export class NaturalComparer {
                 if (vx !== vy) return vx < vy ? -1 : 1;
             } else {
                 // Ordinal comparison like char.ToUpperInvariant(cx).CompareTo(...) in the C# version
-                const ux = cx.toUpperCase();
-                const uy = cy.toUpperCase();
+                const ux = this.toUpperChar(cx);
+                const uy = this.toUpperChar(cy);
                 if (ux !== uy) return ux < uy ? -1 : 1;
                 i++;
                 j++;
@@ -35,4 +35,10 @@ export class NaturalComparer {
     private isDigit(c: string): boolean {
         return c >= '0' && c <= '9';
     }
+
+    // char.ToUpperInvariant keeps characters without a single-char upper case (e.g. 'ß' -> 'SS' in JS)
+    private toUpperChar(c: string): string {
+        const upper = c.toUpperCase();
+        return upper.length === 1 ? upper : c;
+    }
 }
diff --git a/TiaCodegen-ts/tests/NaturalComparer.test.ts b/TiaCodegen-ts/tests/NaturalComparer.test.ts
index 63dd2b8..7ad12e1 100644
--- a/TiaCodegen-ts/tests/NaturalComparer.test.ts
+++ b/TiaCodegen-ts/tests/NaturalComparer.test.ts
@@ -12,4 +12,10 @@ describe('NaturalComparer', () => {
         expect(comparer.compare('a2', 'a10')).toBeLessThan(0);
         expect(comparer.compare('a', 'A')).toBe(0);
     });
+
+    test('keeps characters without a single-char upper case like C# ToUpperInvariant', () => {
+        const comparer = new NaturalComparer();
+        expect(comparer.compare('xßy', 'xzy')).toBeGreaterThan(0);
+        expect(comparer.compare('xßy', 'xÜy')).toBeGreaterThan(0);
+    });
 });