diff --git a/Library/Homebrew/os/linux/hardware.rb b/Library/Homebrew/os/linux/hardware.rb
index 433092c45b..b323cbab51 100644
--- a/Library/Homebrew/os/linux/hardware.rb
+++ b/Library/Homebrew/os/linux/hardware.rb
@@ -1,6 +1,6 @@
 module LinuxCPUs
-  OPTIMIZATION_FLAGS = {}
-  def optimization_flags; OPTIMIZATION_FLAGS.dup; end
+  OPTIMIZATION_FLAGS = {}.freeze
+  def optimization_flags; OPTIMIZATION_FLAGS; end
 
   def type
     @cpu_type ||= case `uname -m`
diff --git a/Library/Homebrew/os/mac/hardware.rb b/Library/Homebrew/os/mac/hardware.rb
index c5e8032614..a4c54b0d8d 100644
--- a/Library/Homebrew/os/mac/hardware.rb
+++ b/Library/Homebrew/os/mac/hardware.rb
@@ -7,8 +7,8 @@ module MacCPUs
     :g4 => '-mcpu=7400',
     :g4e => '-mcpu=7450',
     :g5 => '-mcpu=970'
-  }
-  def optimization_flags; OPTIMIZATION_FLAGS.dup; end
+  }.freeze
+  def optimization_flags; OPTIMIZATION_FLAGS; end
 
   # These methods use info spewed out by sysctl.
   # Look in <mach/machine.h> for decoding info.