diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index f00e10f..c40c2b6 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -257,13 +257,15 @@
 into the OpenBMC project.
 
 
-Avoid references to non-public resources
+References to non-public resources
 ----------------------------------------
 
-Code and commit messages should not refer to companies' internal documents
+Code and commit messages shall not refer to companies' internal documents
 or systems (including bug trackers). Other developers may not have access to
 these, making future maintenance difficult.
 
+Code contributed to OpenBMC must build from the publicly available sources,
+with no dependencies on non-public resources (URLs, repositories, etc).
 
 Best practices for D-Bus interfaces
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