diff --git a/dom/plugins/test/unit/xpcshell.ini b/dom/plugins/test/unit/xpcshell.ini
index 69b6731b20..2665c82b50 100644
--- a/dom/plugins/test/unit/xpcshell.ini
+++ b/dom/plugins/test/unit/xpcshell.ini
@@ -5,7 +5,6 @@ tail =
 tags = addons
 firefox-appdir = browser
 support-files =
-  !/toolkit/mozapps/webextensions/test/xpcshell/head_addons.js
 
 [test_allowed_types.js]
 skip-if = appname == "thunderbird"
diff --git a/services/sync/tests/unit/xpcshell.ini b/services/sync/tests/unit/xpcshell.ini
index 5a90652b84..609003ce9f 100644
--- a/services/sync/tests/unit/xpcshell.ini
+++ b/services/sync/tests/unit/xpcshell.ini
@@ -13,7 +13,6 @@ support-files =
   sync_ping_schema.json
   systemaddon-search.xml
   !/services/common/tests/unit/head_helpers.js
-  !/toolkit/mozapps/webextensions/test/xpcshell/head_addons.js
   !/toolkit/components/webextensions/test/xpcshell/head_sync.js
 
 # The manifest is roughly ordered from low-level to high-level. When making
diff --git a/toolkit/components/telemetry/tests/unit/xpcshell.ini b/toolkit/components/telemetry/tests/unit/xpcshell.ini
index fe58d362ea..42354c4cdd 100644
--- a/toolkit/components/telemetry/tests/unit/xpcshell.ini
+++ b/toolkit/components/telemetry/tests/unit/xpcshell.ini
@@ -15,7 +15,6 @@ support-files =
   system.xpi
   restartless.xpi
   theme.xpi
-  !/toolkit/mozapps/webextensions/test/xpcshell/head_addons.js
 generated-files =
   dictionary.xpi
   experiment.xpi