diff --git a/Library/Homebrew/Gemfile b/Library/Homebrew/Gemfile
index f966e88a81..e644c41c96 100644
--- a/Library/Homebrew/Gemfile
+++ b/Library/Homebrew/Gemfile
@@ -33,7 +33,7 @@ group :sorbet, optional: true do
 end
 
 # vendored gems
-gem "activesupport"
+gem "activesupport", "< 7" # 7 requires Ruby 2.7
 gem "concurrent-ruby"
 gem "did_you_mean" # remove when HOMEBREW_REQUIRED_RUBY_VERSION >= 2.7
 gem "mechanize"
diff --git a/Library/Homebrew/Gemfile.lock b/Library/Homebrew/Gemfile.lock
index 8d38b475b9..5e7f616f49 100644
--- a/Library/Homebrew/Gemfile.lock
+++ b/Library/Homebrew/Gemfile.lock
@@ -201,7 +201,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  activesupport
+  activesupport (< 7)
   bootsnap
   byebug
   concurrent-ruby