diff --git a/b2g/chrome/content/forms.js b/b2g/chrome/content/forms.js
index f80b4eddc18..5a348560600 100644
--- a/b2g/chrome/content/forms.js
+++ b/b2g/chrome/content/forms.js
@@ -118,13 +118,28 @@ let FormAssistant = {
 
       case "Forms:Select:Choice":
         let options = target.options;
+        let valueChanged = false;
         if ("index" in json) {
-          options.item(json.index).selected = true;
+          if (options.selectedIndex != json.index) {
+            options.selectedIndex = json.index;
+            valueChanged = true;
+          }
         } else if ("indexes" in json) {
           for (let i = 0; i < options.length; i++) {
-            options.item(i).selected = (json.indexes.indexOf(i) != -1);
+            let newValue = (json.indexes.indexOf(i) != -1);
+            if (options.item(i).selected != newValue) {
+              options.item(i).selected = newValue;
+              valueChanged = true;
+            }
           }
         }
+
+        // only fire onchange event if any selected option is changed
+        if (valueChanged) {
+          let event = content.document.createEvent('HTMLEvents');
+          event.initEvent('change', true, true);
+          target.dispatchEvent(event);
+        }
         break;
     }
   },