diff --git a/app/src/main/java/eu/faircode/email/BoundaryCallbackMessages.java b/app/src/main/java/eu/faircode/email/BoundaryCallbackMessages.java
index 69a04fa0ec..2faa63d63b 100644
--- a/app/src/main/java/eu/faircode/email/BoundaryCallbackMessages.java
+++ b/app/src/main/java/eu/faircode/email/BoundaryCallbackMessages.java
@@ -387,7 +387,7 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
 
                                         if (!protocol.supportsUtf8()) {
                                             search = search.replace("ß", "ss"); // Eszett
-                                            search = Normalizer.normalize(search, Normalizer.Form.NFD)
+                                            search = Normalizer.normalize(search, Normalizer.Form.NFKD)
                                                     .replaceAll("[^\\p{ASCII}]", "");
                                         }