diff --git a/application/Address/AddressController.php b/application/Address/AddressController.php
index 319b63571..7a10638df 100644
--- a/application/Address/AddressController.php
+++ b/application/Address/AddressController.php
@@ -79,7 +79,15 @@ class AddressController extends mfBaseController {
       
       if(array_key_exists("kunde", $filter) && $filter["kunde"]) {
         $kunde = $this->db()->escape($filter['kunde']);
-        $new_filter['add-where'] .= " AND (company like '%$kunde%' OR firstname like '%$kunde%' OR lastname like '%$kunde%' OR concat(firstname, ' ', lastname) like '%$kunde%' OR concat(lastname, ' ', firstname) like '%$kunde%')";
+        // if kunde contains ß or ss we want to search both cases but not with % because it can lead to wrong results
+        if (strpos($kunde, "ß") !== false || strpos($kunde, "ss") !== false) {
+          $kundeWithSS = str_replace("ß", "ss", $kunde);
+          $kundeWithoutSS = str_replace("ss", "ß", $kunde);
+          $new_filter['add-where'] .= " AND (company like '%$kundeWithoutSS%' OR firstname like '%$kundeWithoutSS%' OR lastname like '%$kundeWithoutSS%' OR concat(firstname, ' ', lastname) like '%$kundeWithoutSS%' OR concat(lastname, ' ', firstname) like '%$kundeWithoutSS%')";
+          $new_filter['add-where'] .= " OR (company like '%$kundeWithSS%' OR firstname like '%$kundeWithSS%' OR lastname like '%$kundeWithSS%' OR concat(firstname, ' ', lastname) like '%$kundeWithSS%' OR concat(lastname, ' ', firstname) like '%$kundeWithSS%')";
+        } else {
+          $new_filter['add-where'] .= " AND (company like '%$kunde%' OR firstname like '%$kunde%' OR lastname like '%$kunde%' OR concat(firstname, ' ', lastname) like '%$kunde%' OR concat(lastname, ' ', firstname) like '%$kunde%')";
+        }
       }
       
       if(!array_key_exists("parents_only", $filter)) {
@@ -110,7 +118,7 @@ class AddressController extends mfBaseController {
         $new_filter[$name] = $value;
       }
     }
-    
+
     return $new_filter;
   }