diff --git a/src/at/xrpc.gleam b/src/at/xrpc.gleam
index 8effe6a..e982f4e 100644
--- a/src/at/xrpc.gleam
+++ b/src/at/xrpc.gleam
@@ -3,6 +3,7 @@
 import at/nsid.{type Nsid}
 import gleam/http.{Get, Https, Post}
 import gleam/http/request.{type Request, Request}
+import gleam/json.{type Json}
 import gleam/option.{type Option, None, Some}
 import gleam/uri.{type Uri}
 
@@ -10,7 +11,7 @@ import gleam/uri.{type Uri}
 
 ///
 /// 
-pub type Client {
+pub opaque type Client {
   Client(host: String, port: Option(Int))
 }
 
@@ -59,15 +60,18 @@ pub fn procedure(
   client: Client,
   path: Nsid,
   parameters: List(#(String, String)),
+  body: Json,
 ) -> Request(String) {
   Request(
     method: Post,
-    headers: [],
-    body: "",
+    headers: [
+      #("content-type", "application/json"),
+    ],
+    body: json.to_string(body),
     scheme: Https,
     host: client.host,
     port: client.port,
-    path: "/xrpx/" <> nsid.to_string(path),
+    path: "/xrpc/" <> nsid.to_string(path),
     query: case parameters {
       [] -> option.None
       _ -> option.Some(uri.query_to_string(parameters))