diff --git a/toolkit/components/places/PlacesUtils.jsm b/toolkit/components/places/PlacesUtils.jsm
index 1c2a9a85066..39a28214751 100644
--- a/toolkit/components/places/PlacesUtils.jsm
+++ b/toolkit/components/places/PlacesUtils.jsm
@@ -1698,7 +1698,7 @@ let GUIDHelper = {
         if (row)
           itemId = row.getResultByIndex(0);
       },
-      handleCompletion: function (aReason) {
+      handleCompletion: aReason => {
         if (aReason == REASON_FINISHED && itemId != -1) {
           deferred.resolve(itemId);
 
@@ -1732,7 +1732,7 @@ let GUIDHelper = {
           guid = row.getResultByIndex(1);
         }
       },
-      handleCompletion: function (aReason) {
+      handleCompletion: aReason => {
         if (aReason == REASON_FINISHED && guid) {
           deferred.resolve(guid);