diff --git a/app/static/wallet.js b/app/static/wallet.js
index 3d488805..d9e8ff50 100644
--- a/app/static/wallet.js
+++ b/app/static/wallet.js
@@ -16,17 +16,37 @@ function hexToBytes(hex) {
   return bytes;
 }
 
+function asciiJson(value) {
+  return JSON.stringify(value).replace(/[\u0080-\uFFFF]/g, (char) => {
+    return `\\u${char.charCodeAt(0).toString(16).padStart(4, "0")}`;
+  });
+}
+
+function compareCodePoints(left, right) {
+  const leftPoints = Array.from(left);
+  const rightPoints = Array.from(right);
+  const limit = Math.min(leftPoints.length, rightPoints.length);
+  for (let index = 0; index < limit; index += 1) {
+    const leftPoint = leftPoints[index].codePointAt(0);
+    const rightPoint = rightPoints[index].codePointAt(0);
+    if (leftPoint !== rightPoint) {
+      return leftPoint - rightPoint;
+    }
+  }
+  return leftPoints.length - rightPoints.length;
+}
+
 function stableJson(value) {
   if (Array.isArray(value)) {
     return `[${value.map(stableJson).join(",")}]`;
   }
   if (value && typeof value === "object") {
     return `{${Object.keys(value)
-      .sort()
-      .map((key) => `${JSON.stringify(key)}:${stableJson(value[key])}`)
+      .sort(compareCodePoints)
+      .map((key) => `${asciiJson(key)}:${stableJson(value[key])}`)
       .join(",")}}`;
   }
-  return JSON.stringify(value);
+  return asciiJson(value);
 }
 
 async function sha256Hex(bytes) {
diff --git a/tests/test_wallet_api.py b/tests/test_wallet_api.py
index 7ba90675..3802413d 100644
--- a/tests/test_wallet_api.py
+++ b/tests/test_wallet_api.py
@@ -1,5 +1,8 @@
 from __future__ import annotations
 
+import json
+import shutil
+import subprocess
 from pathlib import Path
 from urllib.parse import parse_qs, urlparse
 
@@ -660,12 +663,62 @@ def test_transfer_action_clears_private_key_after_submit_attempt() -> None:
     transfer_start = wallet_js.find("function setupTransfer()")
     github_actions_start = wallet_js.find("function setupGithubActions()")
     transfer_block = wallet_js[transfer_start:github_actions_start]
+    set_result = 'setText("[data-transfer-result]", transfer);'
+    set_error = 'setText("[data-transfer-result]", error.message);'
+    finally_block = "} finally {"
+    clear_private_key = "clearPrivateKeyField(form);"
 
     assert 'form[data-action="submit-transfer"]' in transfer_block
-    assert 'setText("[data-transfer-result]", transfer);' in transfer_block
-    assert 'setText("[data-transfer-result]", error.message);' in transfer_block
-    assert "} finally {" in transfer_block
-    assert "clearPrivateKeyField(form);" in transfer_block
+    idx_set_result = transfer_block.find(set_result)
+    idx_set_error = transfer_block.find(set_error, idx_set_result)
+    idx_finally = transfer_block.find(finally_block, idx_set_error)
+    idx_clear_private_key = transfer_block.find(clear_private_key, idx_finally)
+
+    assert -1 not in {
+        idx_set_result,
+        idx_set_error,
+        idx_finally,
+        idx_clear_private_key,
+    }
+    assert idx_set_result < idx_set_error < idx_finally < idx_clear_private_key
+
+
+def test_wallet_js_canonicalizes_unicode_like_server() -> None:
+    node = shutil.which("node")
+    if node is None:
+        pytest.skip("node is required to execute wallet.js canonicalization")
+    wallet_js = Path("app/static/wallet.js").read_text(encoding="utf-8")
+    payload = {
+        "type": "mrwk_transfer_v1",
+        "from_address": "mrwk1aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+        "to_address": "mrwk1bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
+        "amount_microunits": 1_500_000,
+        "nonce": 7,
+        "memo": "café 😀",
+        "\ue000": 1,
+        "😀": 2,
+    }
+    node_script = f"""
+const vm = require("vm");
+const context = {{
+  console,
+  TextEncoder,
+  Uint8Array,
+  crypto: {{subtle: {{}}}},
+  document: {{querySelector: () => null, getElementById: () => null}},
+}};
+vm.createContext(context);
+vm.runInContext({json.dumps(wallet_js)}, context);
+console.log(vm.runInContext(`stableJson({json.dumps(payload)})`, context));
+"""
+    result = subprocess.run(
+        [node, "-e", node_script],
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+
+    assert result.stdout.strip() == canonical_wallet_json(payload)
 
 
 def test_reject_self_transfer(sqlite_url: str) -> None: