diff --git a/Library/Homebrew/build_environment.rb b/Library/Homebrew/build_environment.rb
index c10c9fb1c4..e6dbf9734a 100644
--- a/Library/Homebrew/build_environment.rb
+++ b/Library/Homebrew/build_environment.rb
@@ -22,8 +22,8 @@ class BuildEnvironment
     @settings.include? :userpaths
   end
 
-  def modify_build_environment(context=nil)
-    @procs.each { |p| ENV.instance_exec(context, &p) }
+  def modify_build_environment(receiver)
+    @procs.each { |p| receiver.instance_eval(&p) }
   end
 
   def _dump(*)
diff --git a/Library/Homebrew/extend/object.rb b/Library/Homebrew/extend/object.rb
deleted file mode 100644
index 8ffe5dc90d..0000000000
--- a/Library/Homebrew/extend/object.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-class Object
-  def instance_exec(*args, &block)
-    method_name = :__temp_instance_exec_method
-    singleton_class = (class << self; self; end)
-    singleton_class.class_eval do
-      define_method(method_name, &block)
-    end
-
-    send(method_name, *args)
-  ensure
-    singleton_class.class_eval do
-      remove_method(method_name) if method_defined?(method_name)
-    end
-  end unless method_defined?(:instance_exec)
-end
diff --git a/Library/Homebrew/global.rb b/Library/Homebrew/global.rb
index 2ae186c822..13c52d02b5 100644
--- a/Library/Homebrew/global.rb
+++ b/Library/Homebrew/global.rb
@@ -3,7 +3,6 @@ require 'extend/pathname'
 require 'extend/ARGV'
 require 'extend/string'
 require 'extend/symbol'
-require 'extend/object'
 require 'utils'
 require 'exceptions'
 require 'set'
diff --git a/Library/Homebrew/requirement.rb b/Library/Homebrew/requirement.rb
index 89423c78b2..42e4467bc5 100644
--- a/Library/Homebrew/requirement.rb
+++ b/Library/Homebrew/requirement.rb
@@ -68,7 +68,7 @@ class Requirement
     when Pathname
       self.class.env do
         unless ENV["PATH"].split(":").include?(o.parent.to_s)
-          append("PATH", o.parent, ":")
+          ENV.append("PATH", o.parent, ":")
         end
       end
     end
diff --git a/Library/Homebrew/requirements.rb b/Library/Homebrew/requirements.rb
index 34273a0f39..881ac4ad18 100644
--- a/Library/Homebrew/requirements.rb
+++ b/Library/Homebrew/requirements.rb
@@ -179,11 +179,11 @@ class MPIDependency < Requirement
     @unknown_langs.empty? and @non_functional.empty?
   end
 
-  env do |req|
+  env do
     # Set environment variables to help configure scripts find MPI compilers.
     # Variable names taken from:
     # http://www.gnu.org/software/autoconf-archive/ax_mpi.html
-    req.lang_list.each do |lang|
+    @lang_list.each do |lang|
       compiler = 'mpi' + lang.to_s
       mpi_path = which compiler
 
diff --git a/Library/Homebrew/test/test_build_environment.rb b/Library/Homebrew/test/test_build_environment.rb
index 31d3cb1cb8..2e1c6a602a 100644
--- a/Library/Homebrew/test/test_build_environment.rb
+++ b/Library/Homebrew/test/test_build_environment.rb
@@ -23,7 +23,7 @@ class BuildEnvironmentTests < Test::Unit::TestCase
   def test_modify_build_environment
     @env << Proc.new { raise StandardError }
     assert_raises(StandardError) do
-      @env.modify_build_environment
+      @env.modify_build_environment(self)
     end
   end
 
@@ -38,7 +38,7 @@ class BuildEnvironmentTests < Test::Unit::TestCase
     foo = mock("foo")
     @env << Proc.new { foo.some_message }
     foo.expects(:some_message)
-    @env.modify_build_environment
+    @env.modify_build_environment(self)
   end
 
   def test_env_block_with_argument
diff --git a/Library/Homebrew/test/test_object.rb b/Library/Homebrew/test/test_object.rb
deleted file mode 100644
index debdd6c42c..0000000000
--- a/Library/Homebrew/test/test_object.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require 'testing_env'
-require 'extend/object'
-
-class InstanceExecTests < Test::Unit::TestCase
-  def test_evaluates_in_context_of_receiver
-    assert_equal 1, [1].instance_exec { first }
-  end
-
-  def test_passes_arguments_to_block
-    assert_equal 2, [1].instance_exec(1) { |x| first + x }
-  end
-
-  def test_does_not_persist_temporary_singleton_method
-    obj = Object.new
-    before = obj.methods
-    obj.instance_exec { methods }
-    after = obj.methods
-    assert_equal before, after
-  end
-end