diff --git a/adaptive_image.module b/adaptive_image.module
index a3c4b5a..1d49baa 100644
--- a/adaptive_image.module
+++ b/adaptive_image.module
@@ -142,6 +142,25 @@ function theme_adaptive_image_scale_summary($variables) {
 }
 
 /**
+ * Validate Input of Resolutions-Field
+ */
+function adaptive_image_form_image_effect_form_alter(&$form, &$form_state, $form_id) {
+  $form['#validate'] = array('_adaptive_image_form_image_effect_form_validate');
+}
+
+function _adaptive_image_form_image_effect_form_validate($form, &$form_state) {
+  $resolutions = $form['data']['resolutions']['#value'];
+  $resolutions = explode(',',$resolutions);
+  foreach($resolutions as $r_width)
+  {
+    $r_width = trim($r_width, ' ');
+    if(!is_numeric($r_width)){
+      form_set_error('Resolutions', t("Values have to be seperated by comma. For example: 1382, 992, 768, 480"));
+    }
+  } 
+}
+
+/**
  * Implements template_preprocess_image().
  *
  * Adds a class to adaptive images for max-width.