diff --git a/lib/templates/test-body-footer.html b/lib/templates/test-body-footer.html
index ba5c8c4e..68885762 100644
--- a/lib/templates/test-body-footer.html
+++ b/lib/templates/test-body-footer.html
@@ -25,9 +25,11 @@
 
     if (REQUEST_ASYNC) {
       request.responseType = 'json';
-      request.onload = function() {
-        handleCoverageResponse(this, callback);
-      }
+      request.onreadystatechange = function() {
+        if (request.readyState === 4) {
+          handleCoverageResponse(this, callback);
+        }
+      };
     } else {
       // The request is already done at this point, since it is synchronous
       if (request.status === 200) {
@@ -47,7 +49,7 @@
   }
 
   function handleCoverageResponse(xhr, callback) {
-    var data = xhr.response;
+    var data = xhr.response || xhr.responseText;
 
     // PhantomJS doesn't honor `responseType = 'json'`
     if (typeof data === 'string') {