diff --git a/js/public/ProtoKey.h b/js/public/ProtoKey.h
index f0cbc05738a6..a4e751d4a5e3 100644
--- a/js/public/ProtoKey.h
+++ b/js/public/ProtoKey.h
@@ -129,8 +129,10 @@
   REAL(ReadableByteStreamController, InitViaClassSpec,                       \
        &js::ReadableByteStreamController::class_)                            \
   REAL(WritableStream, InitViaClassSpec, &js::WritableStream::class_)        \
-  IMAGINARY(WritableStreamDefaultWriter, dummy, dummy)                       \
-  IMAGINARY(WritableStreamDefaultController, dummy, dummy)                   \
+  REAL(WritableStreamDefaultController, InitViaClassSpec,                    \
+       &js::WritableStreamDefaultController::class_)                         \
+  REAL(WritableStreamDefaultWriter, InitViaClassSpec,                        \
+       &js::WritableStreamDefaultWriter::class_)                             \
   REAL(ByteLengthQueuingStrategy, InitViaClassSpec,                          \
        &js::ByteLengthQueuingStrategy::class_)                               \
   REAL(CountQueuingStrategy, InitViaClassSpec,                               \
diff --git a/js/src/vm/GlobalObject.cpp b/js/src/vm/GlobalObject.cpp
index eb89c318d414..de364042762a 100644
--- a/js/src/vm/GlobalObject.cpp
+++ b/js/src/vm/GlobalObject.cpp
@@ -36,6 +36,8 @@
 #include "builtin/streams/ReadableStreamController.h"  // js::Readable{StreamDefault,ByteStream}Controller
 #include "builtin/streams/ReadableStreamReader.h"  // js::ReadableStreamDefaultReader
 #include "builtin/streams/WritableStream.h"        // js::WritableStream
+#include "builtin/streams/WritableStreamDefaultController.h"  // js::WritableStreamDefaultController
+#include "builtin/streams/WritableStreamDefaultWriter.h"  // js::WritableStreamDefaultWriter
 #include "builtin/Symbol.h"
 #include "builtin/TypedObject.h"
 #include "builtin/WeakMapObject.h"
@@ -122,7 +124,9 @@ bool GlobalObject::skipDeselectedConstructor(JSContext* cx, JSProtoKey key) {
     case JSProto_CountQueuingStrategy:
       return !cx->realm()->creationOptions().getStreamsEnabled();
 
-    case JSProto_WritableStream: {
+    case JSProto_WritableStream:
+    case JSProto_WritableStreamDefaultController:
+    case JSProto_WritableStreamDefaultWriter: {
       const auto& realmOptions = cx->realm()->creationOptions();
       return !realmOptions.getStreamsEnabled() ||
              !realmOptions.getWritableStreamsEnabled();