diff --git a/src/workerd/api/http.c++ b/src/workerd/api/http.c++
index 7555aa80506..c5cc67aa7fd 100644
--- a/src/workerd/api/http.c++
+++ b/src/workerd/api/http.c++
@@ -704,6 +704,12 @@ Body::ExtractedBody Body::extractBody(jsg::Lock& js, Initializer init) {
       contentType = type.toString();
       buffer = searchParams->toString();
     }
+    KJ_CASE_ONEOF(searchParams, jsg::Ref<url::URLSearchParams>) {
+      auto type = MimeType::FORM_URLENCODED.clone();
+      type.addParam("charset"_kj, "UTF-8"_kj);
+      contentType = type.toString();
+      buffer = searchParams->toString();
+    }
   }
 
   auto bodyStream = kj::heap<BodyBufferInputStream>(buffer.clone(js));
diff --git a/src/workerd/api/http.h b/src/workerd/api/http.h
index b1d90f8b8fc..ee3672b195f 100644
--- a/src/workerd/api/http.h
+++ b/src/workerd/api/http.h
@@ -14,6 +14,7 @@
 #include "form-data.h"
 #include "web-socket.h"
 #include <workerd/api/url.h>
+#include <workerd/api/url-standard.h>
 #include "blob.h"
 #include <workerd/io/compatibility-date.capnp.h>
 #include "worker-rpc.h"
@@ -252,7 +253,8 @@ class Body: public jsg::Object {
   // from any of the other source types, Body can create a new ReadableStream from the source, and
   // the POST will successfully retransmit.
   using Initializer = kj::OneOf<jsg::Ref<ReadableStream>, kj::String, kj::Array<byte>,
-                                jsg::Ref<Blob>, jsg::Ref<URLSearchParams>, jsg::Ref<FormData>>;
+                                jsg::Ref<Blob>, jsg::Ref<FormData>,
+                                jsg::Ref<URLSearchParams>, jsg::Ref<url::URLSearchParams>>;
 
   struct RefcountedBytes final: public kj::Refcounted {
     kj::Array<kj::byte> bytes;