diff --git a/dom/serviceworkers/test/test_serviceworker_interfaces.js b/dom/serviceworkers/test/test_serviceworker_interfaces.js
index e36646b11105..7cbae92359e6 100644
--- a/dom/serviceworkers/test/test_serviceworker_interfaces.js
+++ b/dom/serviceworkers/test/test_serviceworker_interfaces.js
@@ -128,8 +128,6 @@ var interfaceNamesInGlobalScope =
     "FileList",
 // IMPORTANT: Do not change this list without review from a DOM peer!
     "FileReader",
-// IMPORTANT: Do not change this list without review from a DOM peer!
-    "FileReaderSync",
 // IMPORTANT: Do not change this list without review from a DOM peer!
     "FormData",
 // IMPORTANT: Do not change this list without review from a DOM peer!
diff --git a/dom/webidl/FileReaderSync.webidl b/dom/webidl/FileReaderSync.webidl
index 8b586f4a7020..6628794f2432 100644
--- a/dom/webidl/FileReaderSync.webidl
+++ b/dom/webidl/FileReaderSync.webidl
@@ -11,7 +11,7 @@
  */
 
 [Constructor,
- Exposed=Worker]
+ Exposed=(DedicatedWorker,SharedWorker)]
 interface FileReaderSync {
 
   // Synchronously return strings
diff --git a/testing/web-platform/meta/FileAPI/historical.https.html.ini b/testing/web-platform/meta/FileAPI/historical.https.html.ini
deleted file mode 100644
index fdd987a2f0ff..000000000000
--- a/testing/web-platform/meta/FileAPI/historical.https.html.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[historical.https.html]
-  ["FileReaderSync" should not be supported in service workers]
-    expected: FAIL
-