diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 2691af055f..7b1d3628f2 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -19,7 +19,7 @@ Prometheus uses GitHub to manage reviews of pull requests.
   Practices for Production
   Environments](https://peter.bourgon.org/go-in-production/#formatting-and-style).
 
-* Be sure to sign off on the [DCO](https://github.com/probot/dco#how-it-works)
+* Be sure to sign off on the [DCO](https://github.com/probot/dco#how-it-works).
 
 
 ## Steps to Contribute