diff --git a/src/errors.js b/src/errors.js
index 84dc5c2c9..030467266 100644
--- a/src/errors.js
+++ b/src/errors.js
@@ -86,12 +86,22 @@ function E(code, message, Base) {
     }
   }
 
-  NodeError.prototype.name = Base.name
+  Object.defineProperties(NodeError.prototype, {
+    name: {
+      value: Base.name,
+      writable: true,
+      enumerable: false,
+      configurable: true,
+    },
+    toString: {
+      value() { return `${this.name} [${code}]: ${this.message}`; },
+      writable: true,
+      enumerable: false,
+      configurable: true,
+    }    
+  });
   NodeError.prototype.code = code
   NodeError.prototype[kIsNodeError] = true
-  NodeError.prototype.toString = function () {
-    return `${this.name} [${code}]: ${this.message}`
-  }
 
   codes[code] = NodeError
 }