diff --git a/lib/internal/util.js b/lib/internal/util.js
index 073879d9e9..055f8779b1 100644
--- a/lib/internal/util.js
+++ b/lib/internal/util.js
@@ -69,7 +69,10 @@ exports._deprecate = function(fn, msg) {
   // The wrapper will keep the same prototype as fn to maintain prototype chain
   Object.setPrototypeOf(deprecated, fn);
   if (fn.prototype) {
-    Object.setPrototypeOf(deprecated.prototype, fn.prototype);
+    // Setting this (rather than using Object.setPrototype, as above) ensures
+    // that calling the unwrapped constructor gives an instanceof the wrapped
+    // constructor.
+    deprecated.prototype = fn.prototype;
   }
 
   return deprecated;
diff --git a/test/fixtures/deprecated-userland-class.js b/test/fixtures/deprecated-userland-class.js
index 867bbbf2ae..075426fd6b 100644
--- a/test/fixtures/deprecated-userland-class.js
+++ b/test/fixtures/deprecated-userland-class.js
@@ -7,6 +7,9 @@ class deprecatedClass {
 const deprecated = util.deprecate(deprecatedClass, 'deprecatedClass is deprecated.');
 
 const instance = new deprecated();
+const deprecatedInstance = new deprecatedClass();
 
 assert(instance instanceof deprecated);
 assert(instance instanceof deprecatedClass);
+assert(deprecatedInstance instanceof deprecated);
+assert(deprecatedInstance instanceof deprecatedClass);