diff --git a/Layout/default/Preorder/Index.php b/Layout/default/Preorder/Index.php
index 3644b4203..4b3b3a097 100644
--- a/Layout/default/Preorder/Index.php
+++ b/Layout/default/Preorder/Index.php
@@ -130,7 +130,7 @@
                   <label class="form-label" for="filter_unit_count">Anzahl GWR Wohneinheiten</label>
                   <select name="filter[unit_count]" id="filter_unit_count" class="form-control">
                     <option value=""></option>
-                    <option value="0" <?=(isset($filter) && array_key_exists("unit_count", $filter) && intval($filter['unit_count']) === 0) ? "selected='selected'" : ""?>>0</option>
+                    <option value="0" <?=(isset($filter) && array_key_exists("unit_count", $filter) && strlen($filter['unit_count']) && intval($filter['unit_count']) === 0) ? "selected='selected'" : ""?>>0</option>
                     <option value="1" <?=(isset($filter) && array_key_exists("unit_count", $filter) && intval($filter['unit_count']) === 1) ? "selected='selected'" : ""?>>1</option>
                     <option value="2" <?=(isset($filter) && array_key_exists("unit_count", $filter) && intval($filter['unit_count']) === 2) ? "selected='selected'" : ""?>> &gt; 1</option>
                   </select>
diff --git a/application/Preorder/PreorderModel.php b/application/Preorder/PreorderModel.php
index 039b694a6..6854b4e21 100644
--- a/application/Preorder/PreorderModel.php
+++ b/application/Preorder/PreorderModel.php
@@ -474,7 +474,7 @@ class PreorderModel {
         $where .= " AND adb_hausnummer.unit_count = 1";
       } elseif(intval($unit_count) === 2) {
         $where .= " AND adb_hausnummer.unit_count > 1";
-      } elseif(intval($unit_count) === 0) {
+      } elseif(strlen($unit_count) && intval($unit_count) === 0) {
         $where .= " AND adb_hausnummer.unit_count = 0 OR adb_hausnummer.unit_count IS NULL";
       }
     }