diff --git a/lib/warn.js b/lib/warn.js
index 7a72bc6..6658805 100644
--- a/lib/warn.js
+++ b/lib/warn.js
@@ -60,8 +60,8 @@ var Warning = exports.Warning = function( e )
     this.name    = 'Warning';
     this._error  = e;
 
-    this.stack = this.stack &&
-        this.stack.replace( /^.*?\n+/,
+    this.stack = e.stack &&
+        e.stack.replace( /^.*?\n+/,
             this.name + ': ' + this.message + "\n"
         );
 };