diff --git a/src/components/App/client-api.ts b/src/components/App/client-api.ts
new file mode 100644
index 00000000..3dc465ea
--- /dev/null
+++ b/src/components/App/client-api.ts
@@ -0,0 +1,37 @@
+import App from './index';
+
+import { expose } from 'comlink';
+
+export function exposeAPI(app: App) {
+  self.parent.postMessage('READY', '*');
+  self.addEventListener('message', (ev: MessageEvent) => {
+    if (ev.data !== 'READY?') {
+      return;
+    }
+    ev.stopPropagation();
+    self.parent.postMessage('READY', '*');
+  });
+  expose(new API(app), self.parent);
+}
+
+class API {
+  constructor(private app: App) { }
+
+  async setFile(blob: Blob, name: string) {
+    await new Promise((resolve) => {
+      this.app.setState({ file: new File([blob], name) }, resolve);
+    });
+    await new Promise((resolve) => {
+      document.addEventListener('squooshingdone', resolve, { once: true });
+    });
+  }
+
+  async getBlob(side: 0 | 1) {
+    if (!this.app.state.file || !this.app.compressInstance) {
+      throw new Error('No file has been loaded');
+    }
+
+    await this.app.compressInstance.compressionJobs[side];
+    return this.app.compressInstance.state.images[side].file;
+  }
+}
diff --git a/src/components/App/index.tsx b/src/components/App/index.tsx
index 0e5a1e9d..7d4e3ded 100644
--- a/src/components/App/index.tsx
+++ b/src/components/App/index.tsx
@@ -36,7 +36,7 @@ export default class App extends Component<Props, State> {
     file: undefined,
     Compress: undefined,
   };
-  private compressInstance?: import('../compress').default;
+  compressInstance?: import('../compress').default;
 
   snackbar?: SnackBarElement;
 
@@ -70,7 +70,7 @@ export default class App extends Component<Props, State> {
     });
 
     window.addEventListener('popstate', this.onPopState);
-    this.exposeAPI();
+    import('./client-api').then(m => m.exposeAPI(this));
   }
 
   @bind
@@ -105,39 +105,6 @@ export default class App extends Component<Props, State> {
     this.setState({ isEditorOpen: true });
   }
 
-  private exposeAPI() {
-    const api = {
-      setFile: async (blob: Blob, name: string) => {
-        let oldCompressorState = this.compressInstance && this.compressInstance.state;
-        await new Promise((resolve) => {
-          this.setState({ file: new File([blob], name) }, resolve);
-        });
-        await new Promise((resolve) => {
-          document.addEventListener('squooshingdone', resolve, { once: true });
-        });
-        if (oldCompressorState) {
-          let newState = this.compressInstance!.state;
-          [0, 1].forEach((index) => {
-            oldCompressorState = cleanMerge(oldCompressorState!, `images.${index}`, {
-              loading: false,
-              data: undefined,
-            });
-            newState = cleanSet(newState, `images.${index}`, oldCompressorState.images[index]);
-          });
-          this.compressInstance!.setState(newState);
-        }
-      },
-      getBlob: async (side: 0 | 1) => {
-        if (!this.state.file || !this.compressInstance) {
-          throw new Error('No file has been loaded');
-        }
-        await this.compressInstance.compressionJobs[side];
-        return this.compressInstance.state.images[side].file;
-      },
-    };
-    expose(api, self.parent);
-  }
-
   render({}: Props, { file, isEditorOpen, Compress }: State) {
     return (
       <div id="app" class={style.app}>