diff --git a/jest.config.js b/jest.config.js
index 29cc8ec7..1773d9d0 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -1,4 +1,5 @@
 module.exports = {
   transformIgnorePatterns: ['[/\\\\]node_modules[/\\\\](?!(axios|is-retry-allowed)).+\\.(js|jsx)$'],
   setupFilesAfterEnv: ['<rootDir>/test/crypto.ts'],
+  setupFiles: ['<rootDir>/setup.jest.js'],
 };
diff --git a/setup.jest.js b/setup.jest.js
new file mode 100644
index 00000000..02b5b2d3
--- /dev/null
+++ b/setup.jest.js
@@ -0,0 +1,3 @@
+import { TextDecoder, TextEncoder } from 'util';
+global.TextEncoder = TextEncoder;
+global.TextDecoder = TextDecoder;
diff --git a/src/webview/client.ts b/src/webview/client.ts
index c8e53a8b..af1c1c91 100644
--- a/src/webview/client.ts
+++ b/src/webview/client.ts
@@ -63,17 +63,21 @@ export const WebViewApi = () => {
     },
 
     getAssets: async (assets: string[], cb: (assets: WebviewAsset[]) => void) => {
+      const cbf = (str: string) => {
+        const assets = JSON.parse(str) as WebviewAsset[];
+        cb(assets);
+      };
       switch (getMixinContext().platform) {
         case 'iOS':
           if (window.webkit && window.webkit.messageHandlers && window.webkit.messageHandlers.getAssets) {
-            window.assetsCallbackFunction = cb;
+            window.assetsCallbackFunction = cbf;
             await window.webkit.messageHandlers.getAssets.postMessage([assets, 'assetsCallbackFunction']);
           }
           break;
         case 'Android':
         case 'Desktop':
           if (window.MixinContext && typeof window.MixinContext.getAssets === 'function') {
-            window.assetsCallbackFunction = cb;
+            window.assetsCallbackFunction = cbf;
             await window.MixinContext.getAssets(assets, 'assetsCallbackFunction');
           }
           break;
diff --git a/src/webview/type.ts b/src/webview/type.ts
index 2a219014..ea6824ba 100644
--- a/src/webview/type.ts
+++ b/src/webview/type.ts
@@ -49,7 +49,7 @@ declare global {
       getTipAddress?: Messengers['getTipAddress'];
       tipSign?: Messengers['tipSign'];
     };
-    assetsCallbackFunction?: (res: WebviewAsset[]) => void;
+    assetsCallbackFunction?: (res: string) => void;
     tipAddressCallbackFunction?: (address: string) => void;
     tipSignCallbackFunction?: (signature: string) => void;
   }