diff --git a/aspnet/web-api/overview/advanced/httpclient-message-handlers/samples/sample2.cs b/aspnet/web-api/overview/advanced/httpclient-message-handlers/samples/sample2.cs
index 5f4c540877..8899a7735d 100644
--- a/aspnet/web-api/overview/advanced/httpclient-message-handlers/samples/sample2.cs
+++ b/aspnet/web-api/overview/advanced/httpclient-message-handlers/samples/sample2.cs
@@ -5,8 +5,8 @@ class MessageHandler1 : DelegatingHandler
     protected override Task<HttpResponseMessage> SendAsync(
         HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
     {
-        _count++;
+        System.Threading.Interlocked.Increment(ref _count);
         request.Headers.Add("X-Custom-Header", _count.ToString());
         return base.SendAsync(request, cancellationToken);
     }
-}
\ No newline at end of file
+}