diff --git a/lib/util.js b/lib/util.js
index f47e39fddda..3161f7e3be2 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -144,7 +144,7 @@ function inspect(obj, showHidden, depth, colors) {
         value !== exports &&
         // Also filter out any prototype objects using the circular check.
         !(value.constructor && value.constructor.prototype === value)) {
-      return value.inspect(recurseTimes);
+      return '' + value.inspect(recurseTimes);
     }
 
     // Primitive types cannot have properties
diff --git a/test/simple/test-util-inspect.js b/test/simple/test-util-inspect.js
index 717182f88de..b929caec5f2 100644
--- a/test/simple/test-util-inspect.js
+++ b/test/simple/test-util-inspect.js
@@ -33,3 +33,11 @@ var orig = util.inspect(d);
 Date2.prototype.foo = 'bar';
 var after = util.inspect(d);
 assert.equal(orig, after);
+
+// .inspect() function that returns a non-string
+// should not trigger an exception
+// https://github.com/joyent/node/issues/410
+var o = {
+  inspect: function() {}
+};
+assert.equal(util.inspect(o), 'undefined');
\ No newline at end of file