diff --git a/core/01_core.js b/core/01_core.js
old mode 100644
new mode 100755
index 71d94741c..e69dc256b
--- a/core/01_core.js
+++ b/core/01_core.js
@@ -644,6 +644,7 @@
   // Extra Deno.core.* exports
   const core = ObjectAssign(globalThis.Deno.core, {
     internalRidSymbol: Symbol("Deno.internal.rid"),
+    internalFdSymbol: Symbol("Deno.internal.fd"),
     resources,
     eventLoopTick,
     BadResource,