diff --git a/docs/extensibility/custom-component.md b/docs/extensibility/custom-component.md
index b66ea0ef2d..0958f5cfe6 100644
--- a/docs/extensibility/custom-component.md
+++ b/docs/extensibility/custom-component.md
@@ -155,6 +155,12 @@ With the component library created, you can now update the Newsletter service to
 dotnet add ./MailDevResource.NewsletterService/MailDevResource.NewsletterService.csproj reference MailKit.Client/MailKit.Client.csproj
 ```
 
+Next, add a reference to the `ServiceDefaults` project:
+
+```dotnetcli
+dotnet add ./MailDevResource.NewsletterService/MailDevResource.NewsletterService.csproj reference MailDevResource.ServiceDefaults/MailDevResource.ServiceDefaults.csproj
+```
+
 The final step is to replace the existing _:::no-loc text="Program.cs":::_ file in the `MailDevResource.NewsletterService` project with the following C# code:
 
 :::code source="snippets/MailDevResourceAndComponent/MailDevResource.NewsletterService/Program.cs":::