diff --git a/src/Form/PopupSettingsForm.php b/src/Form/PopupSettingsForm.php
index 83b8ced..4a25a5d 100644
--- a/src/Form/PopupSettingsForm.php
+++ b/src/Form/PopupSettingsForm.php
@@ -178,12 +178,14 @@ class PopupSettingsForm extends ConfigFormBase {
       '#title' => $this->t('Delay'),
       '#description' => $this->t('Show message after the enter number of seconds. Enter 0 to show instantly.'),
       '#default_value' => $config->get('delay'),
+      '#min' => 0,
     ];
 
     $form['popup_settings']['popup_top_position'] = [
       '#type' => 'number',
       '#title' => $this->t('Top Offset'),
       '#description' => $this->t('Set the offset in px how much the popup box should be away from the top edge of the screen.'),
+      '#min' => 0,
       '#default_value' => $config->get('popup_top_position'),
     ];
     $popup_interval = !empty($config->get('popup_interval')) ? $config->get('popup_interval') : 1;