diff --git a/apps/js-sdk/firecrawl/src/global.d.ts b/apps/js-sdk/firecrawl/src/global.d.ts
new file mode 100644
index 000000000..bf9177ded
--- /dev/null
+++ b/apps/js-sdk/firecrawl/src/global.d.ts
@@ -0,0 +1,5 @@
+export {};
+
+declare global {
+  const __WEBSOCKET_LOADER__: string;
+}
\ No newline at end of file
diff --git a/apps/js-sdk/firecrawl/src/index.ts b/apps/js-sdk/firecrawl/src/index.ts
index 29fabf5d6..c1cc53955 100644
--- a/apps/js-sdk/firecrawl/src/index.ts
+++ b/apps/js-sdk/firecrawl/src/index.ts
@@ -1,9 +1,16 @@
 import axios, { type AxiosResponse, type AxiosRequestHeaders, AxiosError } from "axios";
 import type * as zt from "zod";
 import { zodToJsonSchema } from "zod-to-json-schema";
-import { WebSocket } from "isows";
+import { WebSocket as IsowsWebSocket } from "isows";
 import { TypedEventTarget } from "typescript-event-target";
 
+
+let WebSocket: typeof IsowsWebSocket;
+
+if (typeof __WEBSOCKET_LOADER__ === 'string') {
+  WebSocket = new Function('return ' + __WEBSOCKET_LOADER__)();
+}
+
 /**
  * Configuration interface for FirecrawlApp.
  * @param apiKey - Optional API key for authentication.
@@ -950,6 +957,11 @@ export class CrawlWatcher extends TypedEventTarget<CrawlWatcherEvents> {
   constructor(id: string, app: FirecrawlApp) {
     super();
     this.id = id;
+    console.log('typeof WebSocket', typeof WebSocket)
+    // @ts-ignore
+    if (typeof WebSocket === "function" && WebSocket.prototype.then) {
+      throw new Error("WebSocket behaves like a Promise, which is unexpected.");
+    }    
     this.ws = new WebSocket(`${app.apiUrl}/v1/crawl/${id}`, app.apiKey);
     this.status = "scraping";
     this.data = [];
diff --git a/apps/js-sdk/firecrawl/tsup.config.ts b/apps/js-sdk/firecrawl/tsup.config.ts
index b3b7e42d5..4d4c80aca 100644
--- a/apps/js-sdk/firecrawl/tsup.config.ts
+++ b/apps/js-sdk/firecrawl/tsup.config.ts
@@ -6,4 +6,13 @@ export default defineConfig({
   dts: true,
   outDir: "dist",
   clean: true,
+  esbuildOptions(options, context) {
+    options.define = {
+      __WEBSOCKET_LOADER__: JSON.stringify(
+        context.format === 'cjs' 
+          ? `const { WebSocket } = require('isows'); WebSocket`
+          : `import('isows').then(m => m.WebSocket)`
+      )
+    };
+  },
 });
\ No newline at end of file