diff --git a/mailnews/test/resources/asyncTestUtils.js b/mailnews/test/resources/asyncTestUtils.js
index fafed668be..6fd3734dde 100644
--- a/mailnews/test/resources/asyncTestUtils.js
+++ b/mailnews/test/resources/asyncTestUtils.js
@@ -173,9 +173,10 @@ function _async_driver() {
         let asyncStack = [];
         dump("*******************************************\n");
         dump("Generator explosion!\n");
-        dump("Unhappiness at: " + ex.filename + ":" + ex.lineNumber + "\n");
+        dump("Unhappiness at: " + (ex.fileName || ex.filename) + ":" + ex.lineNumber + "\n");
         dump("Because: " + ex + "\n");
-        dump("Stack:\n  " + ex.stack.replace(/\n/g, "\n  ") + "\n");
+        if (ex.stack)
+          dump("Stack:\n  " + ex.stack.replace(/\n/g, "\n  ") + "\n");
         dump("**** Async Generator Stack source functions:\n");
         for (let i = asyncGeneratorStack.length - 1; i >= 0; i--) {
           dump("  " + asyncGeneratorStack[i][1] + "\n");
diff --git a/mailnews/test/resources/logHelper.js b/mailnews/test/resources/logHelper.js
index 633624d57d..c9d5a1e1f6 100644
--- a/mailnews/test/resources/logHelper.js
+++ b/mailnews/test/resources/logHelper.js
@@ -478,7 +478,7 @@ function _normalize_for_json(aObj, aDepthAllowed, aJsonMeNotNeeded) {
     return {
       type: "error",
       message: "nsIException: " + aObj.name,
-      fileName: aObj.filename,
+      fileName: aObj.filename, // intentionally lower-case
       lineNumber: aObj.lineNumber,
       name: aObj.name,
       result: aObj.result,