diff --git a/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp b/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
index a12e3f28bd..a7d5395698 100644
--- a/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
+++ b/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
@@ -744,9 +744,7 @@ void fetch_response_handover(JS::Realm& realm, Infrastructure::FetchParams const
         transform_stream->set_up(identity_transform_algorithm, flush_algorithm);
 
         // 4. Set internalResponse’s body’s stream to the result of internalResponse’s body’s stream piped through transformStream.
-        auto promise = internal_response->body()->stream()->piped_through(transform_stream->writable());
-        WebIDL::mark_promise_as_handled(*promise);
-        internal_response->body()->set_stream(transform_stream->readable());
+        internal_response->body()->set_stream(internal_response->body()->stream()->piped_through(transform_stream));
     }
 
     // 8. If fetchParams’s process response consume body is non-null, then:
diff --git a/Libraries/LibWeb/Streams/ReadableStream.cpp b/Libraries/LibWeb/Streams/ReadableStream.cpp
index 742277848c..91e1373e08 100644
--- a/Libraries/LibWeb/Streams/ReadableStream.cpp
+++ b/Libraries/LibWeb/Streams/ReadableStream.cpp
@@ -18,6 +18,7 @@
 #include <LibWeb/Streams/ReadableStreamBYOBRequest.h>
 #include <LibWeb/Streams/ReadableStreamDefaultController.h>
 #include <LibWeb/Streams/ReadableStreamDefaultReader.h>
+#include <LibWeb/Streams/TransformStream.h>
 #include <LibWeb/Streams/UnderlyingSource.h>
 #include <LibWeb/Streams/WritableStream.h>
 #include <LibWeb/WebIDL/Buffers.h>
@@ -426,19 +427,25 @@ void ReadableStream::set_up_with_byte_reading_support(GC::Ptr<PullAlgorithm> pul
 }
 
 // https://streams.spec.whatwg.org/#readablestream-pipe-through
-GC::Ref<WebIDL::Promise> ReadableStream::piped_through(GC::Ref<WritableStream> writable, bool prevent_close, bool prevent_abort, bool prevent_cancel, JS::Value signal)
+GC::Ref<ReadableStream> ReadableStream::piped_through(GC::Ref<TransformStream> transform, bool prevent_close, bool prevent_abort, bool prevent_cancel, JS::Value signal)
 {
     // 1. Assert: ! IsReadableStreamLocked(readable) is false.
     VERIFY(!is_readable_stream_locked(*this));
 
-    // 2. Assert: ! IsWritableStreamLocked(writable) is false.
-    VERIFY(!is_writable_stream_locked(writable));
+    // 2. Assert: ! IsWritableStreamLocked(transform.[[writable]]) is false.
+    VERIFY(!is_writable_stream_locked(transform->writable()));
 
     // 3. Let signalArg be signal if signal was given, or undefined otherwise.
     // NOTE: Done by default arguments.
 
-    // 4. Return ! ReadableStreamPipeTo(readable, writable, preventClose, preventAbort, preventCancel, signalArg).
-    return readable_stream_pipe_to(*this, writable, prevent_close, prevent_abort, prevent_cancel, signal);
+    // 4. Let promise be ! ReadableStreamPipeTo(readable, transform.[[writable]], preventClose, preventAbort, preventCancel, signalArg).
+    auto promise = readable_stream_pipe_to(*this, transform->writable(), prevent_close, prevent_abort, prevent_cancel, signal);
+
+    // 5. Set promise.[[PromiseIsHandled]] to true.
+    WebIDL::mark_promise_as_handled(*promise);
+
+    // 6. Return transform.[[readable]].
+    return transform->readable();
 }
 
 }
diff --git a/Libraries/LibWeb/Streams/ReadableStream.h b/Libraries/LibWeb/Streams/ReadableStream.h
index 5cfc1e66dc..af7e9f4fd8 100644
--- a/Libraries/LibWeb/Streams/ReadableStream.h
+++ b/Libraries/LibWeb/Streams/ReadableStream.h
@@ -109,7 +109,7 @@ public:
     WebIDL::ExceptionOr<void> pull_from_bytes(ByteBuffer);
     WebIDL::ExceptionOr<void> enqueue(JS::Value chunk);
     void set_up_with_byte_reading_support(GC::Ptr<PullAlgorithm> = {}, GC::Ptr<CancelAlgorithm> = {}, double high_water_mark = 0);
-    GC::Ref<WebIDL::Promise> piped_through(GC::Ref<WritableStream>, bool prevent_close = false, bool prevent_abort = false, bool prevent_cancel = false, JS::Value signal = JS::js_undefined());
+    GC::Ref<ReadableStream> piped_through(GC::Ref<TransformStream>, bool prevent_close = false, bool prevent_abort = false, bool prevent_cancel = false, JS::Value signal = JS::js_undefined());
 
     GC::Ptr<WebIDL::ArrayBufferView> current_byob_request_view();