diff --git a/utils/CipherUtils.py b/utils/CipherUtils.py
index bebc63e..78adc3b 100644
--- a/utils/CipherUtils.py
+++ b/utils/CipherUtils.py
@@ -64,7 +64,7 @@ def transform_invalid_chars(input: str) -> str:
     """
     res = input
     res = res.replace('ä', 'ae')
-    res = res.replace('A', 'Ae')
+    res = res.replace('Ä', 'Ae')
     res = res.replace('ö', 'oe')
     res = res.replace('Ö', 'Oe')
     res = res.replace('ü', 'ue')