diff --git a/tests/wpt/metadata/FileAPI/idlharness.html.ini b/tests/wpt/metadata/FileAPI/idlharness.html.ini
index 1957439c798..a2b56459bec 100644
--- a/tests/wpt/metadata/FileAPI/idlharness.html.ini
+++ b/tests/wpt/metadata/FileAPI/idlharness.html.ini
@@ -30,3 +30,12 @@
   [FileReader interface: calling readAsArrayBuffer(Blob) on new FileReader() with too few arguments must throw TypeError]
     expected: FAIL
 
+  [FileReader interface: operation readAsBinaryString(Blob)]
+    expected: FAIL
+
+  [FileReader interface: new FileReader() must inherit property "readAsBinaryString" with the proper type (1)]
+    expected: FAIL
+
+  [FileReader interface: calling readAsBinaryString(Blob) on new FileReader() with too few arguments must throw TypeError]
+    expected: FAIL
+
diff --git a/tests/wpt/metadata/FileAPI/idlharness.worker.js.ini b/tests/wpt/metadata/FileAPI/idlharness.worker.js.ini
index 65c6bf4be78..1c1a2484345 100644
--- a/tests/wpt/metadata/FileAPI/idlharness.worker.js.ini
+++ b/tests/wpt/metadata/FileAPI/idlharness.worker.js.ini
@@ -54,15 +54,27 @@
   [Event interface: existence and properties of interface object]
     expected: FAIL
 
-  [Blob interface: existence and properties of interface object]
+  [FileReader interface: operation readAsBinaryString(Blob)]
     expected: FAIL
 
-  [File interface: existence and properties of interface object]
+  [FileReader interface: new FileReader() must inherit property "readAsBinaryString" with the proper type (1)]
     expected: FAIL
 
-  [FileList interface: existence and properties of interface object]
+  [FileReader interface: calling readAsBinaryString(Blob) on new FileReader() with too few arguments must throw TypeError]
     expected: FAIL
 
-  [FileReader interface: existence and properties of interface object]
+  [FileReaderSync interface: operation readAsBinaryString(Blob)]
+    expected: FAIL
+
+  [FileReaderSync interface: new FileReaderSync() must inherit property "readAsBinaryString" with the proper type (1)]
+    expected: FAIL
+
+  [FileReaderSync interface: calling readAsBinaryString(Blob) on new FileReaderSync() with too few arguments must throw TypeError]
+    expected: FAIL
+
+  [FileReaderSync interface: new FileReaderSync() must inherit property "readAsText" with the proper type (2)]
+    expected: FAIL
+
+  [FileReaderSync interface: new FileReaderSync() must inherit property "readAsDataURL" with the proper type (3)]
     expected: FAIL
 
diff --git a/tests/wpt/web-platform-tests/FileAPI/idlharness.idl b/tests/wpt/web-platform-tests/FileAPI/idlharness.idl
index 62e6c5d9f21..d8f31b43a80 100644
--- a/tests/wpt/web-platform-tests/FileAPI/idlharness.idl
+++ b/tests/wpt/web-platform-tests/FileAPI/idlharness.idl
@@ -1,5 +1,7 @@
-[Constructor,
- Constructor(sequence<(ArrayBuffer or ArrayBufferView or Blob or DOMString)> blobParts, optional BlobPropertyBag options), Exposed=Window,Worker]
+// https://w3c.github.io/FileAPI/#idl-index
+
+[Constructor(optional sequence<BlobPart> blobParts, optional BlobPropertyBag options),
+Exposed=(Window,Worker)]
 interface Blob {
 
   readonly attribute unsigned long long size;
@@ -9,8 +11,8 @@ interface Blob {
   //slice Blob into byte-ranged chunks
 
   Blob slice([Clamp] optional long long start,
-             [Clamp] optional long long end,
-             optional DOMString contentType);
+            [Clamp] optional long long end,
+            optional DOMString contentType);
   void close();
 
 };
@@ -19,32 +21,33 @@ dictionary BlobPropertyBag {
   DOMString type = "";
 };
 
-[Constructor(sequence<(Blob or DOMString or ArrayBufferView or ArrayBuffer)> fileBits,
-[EnsureUTF16] DOMString fileName, optional FilePropertyBag options), Exposed=Window,Worker]
-interface File : Blob {
+typedef (BufferSource or Blob or USVString) BlobPart;
 
+[Constructor(sequence<BlobPart> fileBits,
+            [EnsureUTF16] DOMString fileName,
+            optional FilePropertyBag options),
+Exposed=(Window,Worker)]
+interface File : Blob {
   readonly attribute DOMString name;
   readonly attribute long long lastModified;
-
 };
 
-dictionary FilePropertyBag {
-
-  DOMString type = "";
+dictionary FilePropertyBag : BlobPropertyBag {
   long long lastModified;
-
 };
 
-[Exposed=Window,Worker] interface FileList {
+[Exposed=(Window,Worker)]
+interface FileList {
   getter File? item(unsigned long index);
   readonly attribute unsigned long length;
 };
 
-[Constructor, Exposed=Window,Worker]
+[Constructor, Exposed=(Window,Worker)]
 interface FileReader: EventTarget {
 
   // async read methods
   void readAsArrayBuffer(Blob blob);
+  void readAsBinaryString(Blob blob);
   void readAsText(Blob blob, optional DOMString label);
   void readAsDataURL(Blob blob);
 
@@ -55,6 +58,7 @@ interface FileReader: EventTarget {
   const unsigned short LOADING = 1;
   const unsigned short DONE = 2;
 
+
   readonly attribute unsigned short readyState;
 
   // File or Blob data
@@ -62,7 +66,7 @@ interface FileReader: EventTarget {
 
   readonly attribute DOMError? error;
 
-  // event handler attributes
+  // event handler content attributes
   attribute EventHandler onloadstart;
   attribute EventHandler onprogress;
   attribute EventHandler onload;
@@ -72,20 +76,19 @@ interface FileReader: EventTarget {
 
 };
 
-partial interface URL {
-
-  static DOMString createObjectURL(Blob blob);
-  static DOMString createFor(Blob blob);
-  static void revokeObjectURL(DOMString url);
-
-};
-
 [Constructor, Exposed=Worker]
 interface FileReaderSync {
-
   // Synchronously return strings
 
   ArrayBuffer readAsArrayBuffer(Blob blob);
+  DOMString readAsBinaryString(Blob blob);
   DOMString readAsText(Blob blob, optional DOMString label);
   DOMString readAsDataURL(Blob blob);
 };
+
+[Exposed=(Window,DedicatedWorker,SharedWorker)]
+partial interface URL {
+  static DOMString createObjectURL(Blob blob);
+  static DOMString createFor(Blob blob);
+  static void revokeObjectURL(DOMString url);
+};