diff --git a/layout/style/test/test_font_loading_api.html b/layout/style/test/test_font_loading_api.html
index 9642126c3a38..9fe92caf2ad1 100644
--- a/layout/style/test/test_font_loading_api.html
+++ b/layout/style/test/test_font_loading_api.html
@@ -307,6 +307,9 @@ function runTest() {
 
   }).then(function() {
 
+    // XXX Disabled this sub-test due to intermittent failures (bug 1076803).
+    return;
+
     // (TEST 18) Test passing valid url() source strings to the FontFace
     // constructor.
     var srcTests = Promise.resolve();