diff --git a/src/js/service.js b/src/js/service.js
index eed9716..b582f48 100644
--- a/src/js/service.js
+++ b/src/js/service.js
@@ -31,7 +31,7 @@ angular.module('focaAbmVehiculo')
                 }
             },
             guardarCisterna: function(cisterna, idx) {
-                if(idx !== -1) {
+                if(idx !== '-1') {
                     //update
                     cisternas[idx] = cisterna;
                 }else {