diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e46d67e418..3f385663c3 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -98,11 +98,15 @@ There are three places to get help:
 ## Badge guidelines
 
 - Shields.io hosts integrations for services which are primarily
-  used by developers or which are widely used by developers
+  used by developers or which are widely used by developers.
 - The left-hand side of a badge should not advertise. It should be a lowercase _noun_
   succinctly describing the meaning of the right-hand side.
 - Except for badges using the `social` style, logos should be _turned off by
   default_.
+- Badges should not obtain data from undocumented or reverse-engineered API endpoints.
+- Badges should not obtain data by scraping web pages - these are likely to break frequently.
+  Whereas API publishers are incentivised to maintain a stable platform for their users,
+  authors of web pages have no such incentive.
 
 ## Badge URLs