1 files changed, 5 insertions, 0 deletions
diff --git a/js/os.ts b/js/os.ts
index 86a2c4943..5dc5521b4 100644
--- a/js/os.ts
+++ b/js/os.ts
@@ -6,6 +6,7 @@ import * as flatbuffers from "./flatbuffers";
 import { TextDecoder } from "./text_encoding";
 import { assert } from "./util";
 import * as util from "./util";
+import { window } from "./window";
 
 /** The current process id of the runtime. */
 export let pid: number;
@@ -168,5 +169,9 @@ export function start(source?: string): msg.StartRes {
 
   setGlobals(startResMsg.pid(), startResMsg.noColor(), startResMsg.execPath()!);
 
+  // Deno.core could ONLY be safely frozen here (not in globals.ts)
+  // since shared_queue.js will modify core properties.
+  Object.freeze(window.Deno.core);
+
   return startResMsg;
 }