diff --git a/app/_layout.tsx b/app/_layout.tsx
index 120e90b5..56e63cdb 100644
--- a/app/_layout.tsx
+++ b/app/_layout.tsx
@@ -1,4 +1,5 @@
 import "expo-webauthn";
+import "../utils/polyfill";
 
 import { AlchemyProvider } from "@alchemy/aa-alchemy";
 import FontAwesome from "@expo/vector-icons/FontAwesome";
@@ -12,7 +13,6 @@ import { StatusBar } from "expo-status-bar";
 import React, { useEffect } from "react";
 import * as Sentry from "sentry-expo";
 import { TamaguiProvider } from "tamagui";
-import { TextEncoder } from "text-encoding";
 import { WagmiProvider, createConfig, custom } from "wagmi";
 
 import metadata from "../package.json";
@@ -79,5 +79,3 @@ export default function RootLayout() {
     </>
   );
 }
-
-global.TextEncoder ??= TextEncoder; // eslint-disable-line @typescript-eslint/no-unnecessary-condition -- polyfill
diff --git a/utils/polyfill.ts b/utils/polyfill.ts
new file mode 100644
index 00000000..0580cd87
--- /dev/null
+++ b/utils/polyfill.ts
@@ -0,0 +1,12 @@
+import { TextEncoder } from "text-encoding";
+
+/* eslint-disable @typescript-eslint/no-unnecessary-condition */
+
+global.TextEncoder ??= TextEncoder;
+
+// @ts-expect-error -- enough for mipd
+global.CustomEvent ??= class {}; // eslint-disable-line @typescript-eslint/no-extraneous-class
+global.window.addEventListener ??= () => {};
+global.window.dispatchEvent ??= () => false;
+
+/* eslint-enable @typescript-eslint/no-unnecessary-condition */
diff --git a/webauthn/src/index.ts b/webauthn/src/index.ts
index 15420deb..3d47705b 100644
--- a/webauthn/src/index.ts
+++ b/webauthn/src/index.ts
@@ -16,7 +16,7 @@ if (ExpoWebauthn) {
     },
   } as CredentialsContainer;
   // @ts-expect-error -- turnkey's webauthn support detection
-  global.window.PublicKeyCredential = {} as PublicKeyCredential;
+  global.window.PublicKeyCredential ??= {} as PublicKeyCredential; // eslint-disable-line @typescript-eslint/no-unnecessary-condition
 }
 
 function stringify(value: unknown) {