diff --git a/toolkit/components/extensions/test/mochitest/mochitest-common.ini b/toolkit/components/extensions/test/mochitest/mochitest-common.ini
index b4d30d71e017..f991466a5161 100644
--- a/toolkit/components/extensions/test/mochitest/mochitest-common.ini
+++ b/toolkit/components/extensions/test/mochitest/mochitest-common.ini
@@ -85,6 +85,7 @@ skip-if = (!debug && android_version == '18') #Bug 1523193
 skip-if = os == 'android' # Android does not support multiple windows.
 [test_ext_contentscript_permission.html]
 [test_ext_cookies.html]
+fail-if = fission
 [test_ext_cookies_containers.html]
 [test_ext_cookies_expiry.html]
 [test_ext_cookies_first_party.html]