diff --git a/lib/internal/process/per_thread.js b/lib/internal/process/per_thread.js
index 35e861df2b73f9..2204d7223bf344 100644
--- a/lib/internal/process/per_thread.js
+++ b/lib/internal/process/per_thread.js
@@ -263,7 +263,9 @@ function buildAllowedFlags() {
 
       // The super constructor consumes `add`, but
       // disallow any future adds.
-      this.add = () => this;
+      Object.defineProperty(this, 'add', {
+        value: () => this
+      });
     }
 
     delete() {