--- a/browser/components/extensions/test/browser/browser_ext_webNavigation_getFrames.js
+++ b/browser/components/extensions/test/browser/browser_ext_webNavigation_getFrames.js
@@ -133,16 +133,19 @@ add_task(function* testWebNavigationFram
     getAllFramesDetails,
     getFrameResults,
   } = yield extension.awaitMessage("webNavigationFrames.done");
 
   is(getAllFramesDetails.length, 3, "expected number of frames found");
   is(getAllFramesDetails.length, collectedDetails.length,
      "number of frames found should equal the number onCompleted events collected");
 
+  is(getAllFramesDetails[0].frameId, 0, "the root frame has the expected frameId");
+  is(getAllFramesDetails[0].parentFrameId, -1, "the root frame has the expected parentFrameId");
+
   // ordered by frameId
   let sortByFrameId = (el1, el2) => {
     let val1 = el1 ? el1.frameId : -1;
     let val2 = el2 ? el2.frameId : -1;
     return val1 - val2;
   };
 
   collectedDetails = collectedDetails.sort(sortByFrameId);