diff --git a/docs/Maintainer-Guidelines.md b/docs/Maintainer-Guidelines.md
index cfffc1ae1e..ea8bf96313 100644
--- a/docs/Maintainer-Guidelines.md
+++ b/docs/Maintainer-Guidelines.md
@@ -88,7 +88,10 @@ implemented!).
 Don't merge any formula updates with failing `brew test`s. If a `test do` block
 is failing it needs to be fixed. This may involve replacing more involved tests
 with those that are more reliable. This is fine: false positives are better than
-false negatives as we don't want to teach maintainers to merge red PRs.
+false negatives as we don't want to teach maintainers to merge red PRs. If the
+test failure is believed to be due to a bug in Homebrew/brew or the CI system,
+that bug must be fixed, or worked around in the formula to yield a passing test,
+before the PR can be merged.
 
 ## Common “gotchas”
 1.  [Ensure you have set your username and email address