diff --git a/src/Resources/contao/dca/tl_leaflet_layer.php b/src/Resources/contao/dca/tl_leaflet_layer.php
index 1df4aa5..50d0f30 100644
--- a/src/Resources/contao/dca/tl_leaflet_layer.php
+++ b/src/Resources/contao/dca/tl_leaflet_layer.php
@@ -457,7 +457,7 @@ $GLOBALS['TL_DCA']['tl_leaflet_layer'] = [
             'exclude'          => true,
             'inputType'        => 'select',
             'options_callback' => ['netzmacht.contao_leaflet_maps.listeners.dca.leaflet', 'getZoomLevels'],
-            'default'          => '',
+            'default'          => null,
             'eval'             => [
                 'maxlength'          => 4,
                 'rgxp'               => 'digit',