diff --git a/Library/Homebrew/.rubocop.yml b/Library/Homebrew/.rubocop.yml
index 625c9a8fcb..c91eaa0f27 100644
--- a/Library/Homebrew/.rubocop.yml
+++ b/Library/Homebrew/.rubocop.yml
@@ -125,6 +125,10 @@ Style/GuardClause:
 Style/HashSyntax:
   EnforcedStyle: ruby19_no_mixed_keys
 
+# would rather freeze too much than too little
+Style/MutableConstant:
+  EnforcedStyle: strict
+
 # LineLength is low enough here to re-enable it.
 Style/IfUnlessModifier:
   Enabled: true