diff --git a/lib/internal/process/per_thread.js b/lib/internal/process/per_thread.js
index 631348dcd3af69..c2be274659e6c7 100644
--- a/lib/internal/process/per_thread.js
+++ b/lib/internal/process/per_thread.js
@@ -15,6 +15,7 @@ const {
   Float64Array,
   NumberMAX_SAFE_INTEGER,
   ObjectFreeze,
+  ObjectDefineProperty,
   ReflectApply,
   RegExpPrototypeExec,
   SafeArrayIterator,
@@ -371,9 +372,15 @@ function buildAllowedFlags() {
       return SetPrototypeValues(this[kInternal].set);
     }
   }
-  NodeEnvironmentFlagsSet.prototype.keys =
-  NodeEnvironmentFlagsSet.prototype[SymbolIterator] =
-    NodeEnvironmentFlagsSet.prototype.values;
+  const flagSetValues = NodeEnvironmentFlagsSet.prototype.values;
+  ObjectDefineProperty(NodeEnvironmentFlagsSet.prototype, SymbolIterator, {
+    __proto__: null,
+    value: flagSetValues,
+  });
+  ObjectDefineProperty(NodeEnvironmentFlagsSet.prototype, 'keys', {
+    __proto__: null,
+    value: flagSetValues,
+  });
 
   ObjectFreeze(NodeEnvironmentFlagsSet.prototype.constructor);
   ObjectFreeze(NodeEnvironmentFlagsSet.prototype);