diff --git a/Library/Homebrew/extend/os/mac/diagnostic.rb b/Library/Homebrew/extend/os/mac/diagnostic.rb
index a162711f0b93e..232596f36f5ca 100644
--- a/Library/Homebrew/extend/os/mac/diagnostic.rb
+++ b/Library/Homebrew/extend/os/mac/diagnostic.rb
@@ -139,7 +139,7 @@ def check_xcode_up_to_date
         # Homebrew/brew is currently using.
         return if GitHub::Actions.env_set?
 
-        return if ENV["HOMEBREW_NO_WARN_OUTDATED_XCODE"]
+        return if Homebrew::EnvConfig.no_warn_outdated_xcode?
 
         # With fake El Capitan for Portable Ruby, we are intentionally not using Xcode 8.
         # This is because we are not using the CLT and Xcode 8 has the 10.12 SDK.