diff --git a/src/bare-agent.js b/src/bare-agent.js
index 0dcdb3d..c3e8019 100644
--- a/src/bare-agent.js
+++ b/src/bare-agent.js
@@ -142,7 +142,7 @@ export async function send_message(message, update_status, sleep) {
       let canister_id = new Principal(ingress.content.canister_id).toString();
       let method_name = ingress.content.method_name;
       let reply = await query(canister_id, ingress_content);
-      update_status(await try_decode(canister_id, method_name, reply), true);
+      update_status(await try_decode(canister_id, method_name, reply.reply.arg, true), true);
     } else {
       // Update call, handle json format of both nano and dfx
       const ingress_content = fromHexString(
@@ -178,7 +178,7 @@ export async function send_message(message, update_status, sleep) {
         } else {
           if (reply.status == "replied") {
             update_status(
-              await try_decode(canister_id, method_name, reply),
+              await try_decode(canister_id, method_name, reply.reply.arg, true),
               true
             );
           } else {
@@ -222,7 +222,7 @@ const getCandid_interface = ({ IDL }) =>
   });
 
 // Try to decode reply using known did files
-async function try_decode(canister_id, method_name, reply) {
+export async function try_decode(canister_id, method_name, msg, isReply) {
   try {
     var did;
     // Try fetch i using __get_candid_interface_tmp_hack.
@@ -271,9 +271,13 @@ async function try_decode(canister_id, method_name, reply) {
             let mod = await eval('import("' + dataUri + '")');
             let services = mod.idlFactory({ IDL });
             let func = lookup(services._fields, method_name);
-            reply = IDL.decode(func.retTypes, Buffer.from(reply.reply.arg));
-            reply = func.retTypes
-              .map((t, i) => t.valueToString(reply[i]))
+            let funcTypes = func.retTypes;
+            if (!isReply) {
+              funcTypes = func.argTypes;
+            }
+            msg = IDL.decode(funcTypes, Buffer.from(msg));
+            msg = funcTypes
+              .map((t, i) => t.valueToString(msg[i]))
               .toString();
           }
         }
@@ -282,5 +286,5 @@ async function try_decode(canister_id, method_name, reply) {
   } catch (err) {
     console.log(err);
   }
-  return reply;
+  return msg;
 }
diff --git a/src/index.js b/src/index.js
index 0f1db1c..249a6fa 100644
--- a/src/index.js
+++ b/src/index.js
@@ -3,7 +3,7 @@ import * as pako from "pako";
 import { HttpAgent, Cbor } from "@dfinity/agent";
 import { Principal } from "@dfinity/principal";
 import { stringify } from "bigint-json-native";
-import { send_message } from "./bare-agent.js";
+import { send_message, try_decode } from "./bare-agent.js";
 
 const data = {
   version: 1,
@@ -125,14 +125,14 @@ async function scan() {
       const unzipped = pako.inflate(gzipped, { to: "string" });
       const message = JSON.parse(unzipped);
       render(res, width, height);
-      prepare_send(message);
+      await prepare_send(message);
     } catch (err) {
       console.log(err);
     }
   }
 }
 
-function prepare_send(message) {
+async function prepare_send(message) {
   scan_paused = true;
   if (input_type == "video") {
     const scan_button = document.getElementById("scan");
@@ -159,17 +159,18 @@ function prepare_send(message) {
     pre.innerText = "Unsupported message format";
     return;
   }
+  const canister_id = new Principal(ingress.content.canister_id);
+  const args = await try_decode(canister_id, ingress.content.method_name, ingress.content.arg, false);
   const text =
     "Request type : " +
     ingress.content.request_type +
     "\nSender       : " +
     new Principal(ingress.content.sender).toString() +
-    "\nCanister id  : " +
-    new Principal(ingress.content.canister_id).toString() +
+    "\nCanister id  : " + canister_id.toString() +
     "\nMethod name  : " +
     ingress.content.method_name +
     "\nArguments    : " +
-    JSON.stringify(ingress.content.arg);
+    JSON.stringify(args, (_, v) => typeof v === 'bigint' ? `${v}n` : v);
   pre.innerText = text;
   var button = document.getElementById("send");
   if (!button) {