diff --git a/packages/firestore/src/platform_browser/browser_platform.ts b/packages/firestore/src/platform_browser/browser_platform.ts
index d1dc1a75124..8ba09fe99a0 100644
--- a/packages/firestore/src/platform_browser/browser_platform.ts
+++ b/packages/firestore/src/platform_browser/browser_platform.ts
@@ -25,6 +25,10 @@ import { NoopConnectivityMonitor } from '../remote/connectivity_monitor_noop';
 import { BrowserConnectivityMonitor } from './browser_connectivity_monitor';
 import { WebChannelConnection } from './webchannel_connection';
 
+// Polyfill for IE
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+const crypto = window.crypto || (window as any).msCrypto;
+
 export class BrowserPlatform implements Platform {
   readonly useProto3Json = true;
   readonly base64Available: boolean;
diff --git a/packages/firestore/src/util/misc.ts b/packages/firestore/src/util/misc.ts
index dd37a9d3b36..e8c52a4fd42 100644
--- a/packages/firestore/src/util/misc.ts
+++ b/packages/firestore/src/util/misc.ts
@@ -31,7 +31,7 @@ export class AutoId {
     let autoId = '';
     while (autoId.length < 20) {
       const bytes = PlatformSupport.getPlatform().randomBytes(40);
-      bytes.forEach(b => {
+      for (const b of Array.from(bytes)) {
         // Length of `chars` is 62. We only take bytes between 0 and 62*4-1
         // (both inclusive). The value is then evenly mapped to indices of `char`
         // via a modulo operation.
@@ -39,7 +39,7 @@ export class AutoId {
         if (autoId.length < 20 && b <= maxValue) {
           autoId += chars.charAt(b % 62);
         }
-      });
+      }
     }
     assert(autoId.length === 20, 'Invalid auto ID: ' + autoId);
     return autoId;