diff --git a/lib/view/customer_exercise_device.dart b/lib/view/customer_exercise_device.dart
index 5e85dfe..6c451e0 100644
--- a/lib/view/customer_exercise_device.dart
+++ b/lib/view/customer_exercise_device.dart
@@ -184,8 +184,8 @@ class CustomerExerciseDevicePage extends StatelessWidget with Trans {
     final bool isEnglish = AppLanguage().appLocal.languageCode == "en";
     this.listDevice = List();
     final devices = bloc.devices;
-    devices.sort((a, b) => a.sort.compareTo(b.sort));
     if (devices != null) {
+      devices.sort((a, b) => a.sort.compareTo(b.sort));
       devices.forEach((element) {
         if (element.place == false) {
           final String url = "asset/image/" + element.imageUrl.substring(7);