diff --git a/src/content/daily-email/2023-08-24.md b/src/content/daily-email/2023-08-24.md
index de35567b..1012ddb3 100644
--- a/src/content/daily-email/2023-08-24.md
+++ b/src/content/daily-email/2023-08-24.md
@@ -9,7 +9,7 @@ tags:
   - test-driven-development
 ---
 
-If you have multiple implementations of a service, as I [mentioned in yesterday's email](), you need to ensure they all provide the same functionality.
+If you have multiple implementations of a service, as I [mentioned in yesterday's email](https://www.oliverdavies.uk/archive/2023/08/23/dont-use-third-party-services-directly), you need to ensure they all provide the same functionality.
 
 You need to be able to run the same tests against each implementation and have them pass.