diff --git a/Library/Homebrew/extend/ENV/std.rb b/Library/Homebrew/extend/ENV/std.rb
index 708117ca8f..97c1bf615d 100644
--- a/Library/Homebrew/extend/ENV/std.rb
+++ b/Library/Homebrew/extend/ENV/std.rb
@@ -231,11 +231,11 @@ module Stdenv
   end
 
   def minimal_optimization
-    self['CFLAGS'] = self['CXXFLAGS'] = "-Os #{SAFE_CFLAGS_FLAGS}"
+    set_cflags "-Os #{SAFE_CFLAGS_FLAGS}"
     macosxsdk unless MacOS::CLT.installed?
   end
   def no_optimization
-    self['CFLAGS'] = self['CXXFLAGS'] = SAFE_CFLAGS_FLAGS
+    set_cflags SAFE_CFLAGS_FLAGS
     macosxsdk unless MacOS::CLT.installed?
   end