diff --git a/dom/workers/test/mochitest.ini b/dom/workers/test/mochitest.ini
index abd0afe225db..f039c9e7d410 100644
--- a/dom/workers/test/mochitest.ini
+++ b/dom/workers/test/mochitest.ini
@@ -148,6 +148,7 @@ tags = mcb
 [test_longThread.html]
 [test_multi_sharedWorker.html]
 [test_multi_sharedWorker_lifetimes.html]
+skip-if = fission # bug 1667955
 [test_navigator.html]
 support-files =
   test_navigator.js
@@ -179,6 +180,7 @@ support-files =
   sharedWorker_thirdparty_window.html
 [test_simpleThread.html]
 [test_suspend.html]
+skip-if = fission # bug 1667955
 [test_terminate.html]
 [test_threadErrors.html]
 [test_threadTimeouts.html]